The Shulchan Aruch OC (226:1) writes that
בא"י אמ"ה שלא חיסר בעולמו כלום וברא בו בריות טובות ואילנות טובות ליהנות בהם בני אדם - "Blessed Are you....who has not left anything lacking in the world and who has created in in good creations and good trees from which people can benefit."
How can we say there is nothing lacking in the world (we don't have a Beis Hamikdash, there seems to be tragedies, etc.) and why do we specifically mention the perfection of this world in this particular blessing about the spring?