I'm not saying low levels spells won't be useful, but a higher level spell will always deal less damage, and really nasty lower levels save or lose spells(like hold person) won't work on higher level foes. A 3.x wizard's hold person was still insanely difficult to save agienst even for a high level foe if they had a bad will save.
The problem with 4e feats, is since most offered small numerical bonuses, it was usually pretty obvious what feats were better than others(it just took some math), and too many feats amounted to "if you qualify you must take it". Feats wear not really used to customize your character, but where more like a math test at level up.