Why are the obstacles in the Underground Chambers in HP1 so easy?

Question

Considering that a wizard trying to get the Philosopher's Stone will probably be a powerful one, why didn't the professors put much more difficult obstacles in the Underground Chambers?

Is it because they already know that the obstacle made by Dumbledore is impossible for an evil wizard to solve?

Edit : To clarify :

The puzzles to enter the Ravenclaw Dormitory are not easier than the puzzle of Snape.

Quirell's mountain troll is probably the easiest one for a powerful dark wizard who does not care about using the killing curse.

McGonagall's chess puzzle is solved by a 11 year old non-professional chess player.

Flitwick's winged keys puzzle is solved by Harry Potter, who is an inexperienced Quidditch player who played Quidditch only for a year (if we don't count his babyhood).

Sprout's Devil's Snare can be solved by using many spells if you don't know that you need fire like Hermione did.

Hagrid's Fluffy can be solved without the precious information that you need music to put it to a sleep.

Answer 1

They are not so easy

• The room with the keys was actually extremely difficult:

  "They're not birds!" Harry said suddenly. "They're keys! Winged keys -- look carefully. So that must mean..." he looked around the chamber while the other two squinted up at the flock of keys. "... yes -- look! Broomsticks! We've got to catch the key to the door!"

  "But there are hundreds of them!"

  Ron examined the lock on the door. "We're looking for a big, old-fashioned one -- probably silver, like the handle."

  —Harry Potter and the Sorcerer's Stone

  It would take forever to try all the keys, so without guessing (as Ron did) that the key would have to match the door, you would be there a very long time.

  Even then, Harry (a highly skilled Seeker) only noticed the key because it had been damaged:

  Not for nothing, though, was Harry the youngest Seeker in a century. He had a knack for spotting things other people didn't. After a minute's weaving about through the whirl of rainbow feathers, he noticed a large silver key that had a bent wing, as if it had already been caught and stuffed roughly into the keyhole.

  —Harry Potter and the Sorcerer's Stone

• Snape's puzzle would certainly have tripped up a number of powerful witches or wizards, who often do not have great reasoning skills:

  "Brilliant," said Hermione. "This isn't magic—it's logic—a puzzle. A lot of the greatest wizards haven't got an ounce of logic, they'd be stuck in here forever."

  —Harry Potter and the Sorcerer's Stone

• Ron may not be a professional chess player, if such things even exist in the wizarding world, but he is certainly made out to be an extraordinary one:

  "First -- to Mr. Ronald Weasley..."

  Ron went purple in the face; he looked like a radish with a bad sunburn. "...for the best-played game of chess Hogwarts has seen in many years, I award Gryffindor house fifty points."

  Gryffindor cheers nearly raised the bewitched ceiling; the stars overhead seemed to quiver. Percy could be heard telling the other prefects, "My brother, you know! My youngest brother! Got past McGonagall's giant chess set!"

  —Harry Potter and the Sorcerer's Stone

  Given the popularity of wizard chess, if no better game has been played in many years within the walls of Hogwarts, Ron must have done very well. Since most Muggles, at least (and likely most wizards and witches) have no idea how to play chess, let alone play well, this obstacle would likely have stopped most intruders straightaway.

• Could Fluffy really have been subdued without knowing his weakness? Many magical creatures are resistant to magic. Hagrid, for example, can shrug off multiple stunning spells due to his giant heritage. We might imagine that the Killing Curse would surely be effective regardless, but we cannot be so sure. The Killing Curse is 100% effective on humans if it hits, but it may not kill all magical creatures. For example, the Patronus is claimed to be the only way of defeating certain creatures, such as the Lethifold or the Dementor. Or consider, for example, the Nudu:

  This East African beast is arguably the most dangerous in the world. A gigantic leopard that moves silently despite its size and whose breath causes disease virulent enough to eliminate entire villages, it has never yet been subdued by fewer than a hundred skilled wizards working together.

  —Fantastic Beasts and Where to Find Them

  Presumably, if a single Killing Curse could defeat a Nudu, it would not take 100 skilled wizards working together. Avada Kedavra could not necessarily kill Fluffy.

---

That said, Dumbledore's obstacle was still intended to be essentially impenetrable. Although many of the others might still have slowed or even stopped the average (or even above-average) witch or wizard, Dumbledore could still rely on the fact that no one with ill intent could retrieve the Stone from the Mirror. More than that—no one who so much as desired to use the Stone could retrieve it. So not simply evil wizards, but frankly almost anyone who knew what it was:

"Ah, now, I'm glad you asked me that. It was one of my more brilliant ideas, and between you and me, that's saying something. You see, only one who wanted to find the Stone—find it, but not use it—would be able to get it, otherwise they'd just see themselves making gold or drinking Elixir of Life."

—Harry Potter and the Sorcerer's Stone

Answer 2

They needed to be easy enough to solve to allow three or four accomplished wizards (like the head of houses at Hogwarts) to disarm them, should the need arise.

The individual protections by themselves likely weren't meant to be impenetrable. For example, The key to unlock the door was flying around in the same room as the door - a difficult, but certainly not impossible puzzle to solve. It seems that Dumbledore and the others meant for the obstacles and puzzles, once you add them up, to make it difficult for anyone unauthorized to gain access. For example, should Dumbledore and the others ever decide that the stone needs to be removed or relocated, the obstacles and puzzles should be easy enough to allow that to happen. They should be easy enough to solve to allow three or four accomplished wizards (like the head of houses at Hogwarts) to disarm them.

Answer 3

true, unless there were a group people each skilled in different things, only then will they be able to do it. one person cannot be good at everything and the challenges are totally different from each other. also some of the challenges are more like you can pass if you are worthy types(Dumbledore's mirror, potion puzzle), like yes, you deserve to take it if you can get it.

I have read a story somewhere about a puzzle being easy or the solution too simple once the solution is known. but to actually get that idea in the first place is the challenge. it just goes on to prove that yes these three were not just your average 11 year olds but were actually better than even some of the elders.

(btw I wouldn't have been able to defeat a magical chess game or even a normal one. Ron is just that brilliant who can equal Hermione herself if he wants while also having a sense of humor.I guess anybody living with the twins end up picking up some qualities). I was always disappointed that JK didn't elaborate Ron's geniusness in the later books and was only used as a comic relief most of the times.In movies it was even worse where Hermione got most of Ron's dialogue. As they say, history is written from winner's point of view or something like that....