Are monks really glass cannons? They're AC's aren't too far behind a fighters; a 20 in Wisdom and Dexterity comes out to a 20 AC, which matches a plate and shield fighter. And their hit die averages out to 1 less hp per level than a fighter.
Wis and Dex 20 don't come cheap. Assuming you use the standard array and put a 15 in Dex and 14 in Wis, and play a Wood Elf getting +2 Dex and +1 Wis, that's 8 points of ability increases - so you'll get there by level 16 assuming you don't take a feat or something. The fighter gets AC 20... well, it depends on how much money the DM gives out, but probably some time between level 6 and 10. And the fighter is free to plow his stat increases into other stats, or even pick up feats.