Maybe 2nd-level spells should still be useful around 5th-7th level because they form about a third or more or your wizard's effective arsenal at those levels? Yeesh. A 5th-level wizard is casting mostly 1st and 2nd level spells, and even at 6th and 7th-level those 2nd-level slots are needed. Ya only get a few 3rd/4th level slots early on. If Magic Missile, Chill Touch, Resist Elements, Blur, Charm Person and such can still be somewhat effective at middle levels, why not Hold Person, Shield, and so on?
3.5 nerfs are absurd. Shield is now just Mage Armor with about 1/100th the duration, and horribly blah. A duration of a few rounds, effectively one combat, is quite fine for a 1st-level spell giving +7 AC, especially when it's self-only for fragile mages that can't effectively use armor. If a 2nd-level wizard uses 2 slots for Mage Armor and Shield, he's only got 1-2 slots left to cast Burning Hands or Sleep against enemies; wasting half his power for the day to protect himself well for 1 combat? Considering that the game is designed with and average of 3-5 encounters per day in mind (when dungeon-crawling at least) that's not at all unreasonable. If you want to run a game with less frequent combat, then by all means, implement a simple houserule that casters can only replenish spells once or twice per week, and you'll find the spells being just as effective in the infrequent-combat game as in the dungeon-crawling game.
Mages do need some way to contribute in battle beyond casting short-lasting Bull's Strength and such. With their pathetic BAB, they can't be expected to hit a lot of enemies even with touch spells. And what's the group going to do when they encounter a Shadow at 3rd-level, if the mage doesn't have Magic Missile? Sure, he might have Magic Weapon instead, but it's such a weak and uninteresting spell that the mage is unlikely to prepare it more than once, and it's not very fun for the mage to spend one round enchanting an ally's weapon and then sitting out the rest of the combat.
Edit: And besides, everyone knows that Scorching Ray and Ray of Enfeeblement are the new Magic Missile! RoE no longer allows a saving throw and Scorching Ray makes venerable and interesting Flaming Sphere seem pathetic......