I disagree. The game shouldn't stop you from using something just because you lack the skill, and ME1 was one of the few modern games that bothers to penalize you for doing it rather than simply prohibiting it.
I'll agree that restriction also doesn't make sense to me, but as you point out, ME2-3 simply eliminated the mechanic entirely ratherthan fixing it.
I was thinking more of the need to collect and reload clips at all? What did that add to the game?
And while I understand that ME3 made the clips more available, in ME2 there was only ever a shortage of you were using a sniper rifle (there simply wasn't enough ammo in the game to allow you to use a sniper rifle exclusively).
As for the rest, since Shepard could no longer miss unless you wanted her to (she would always hit the target at which she aimed), there was no risk of running out of clips.
Have only played ME2 a single time, but have hundreds of hours now in ME3, and things have improved at least a little.
Thermal clips are still extant, but so are a few weapons with cooldowns. Instead of purchasing various ammo types, certain classes have abilities which activates effects; a couple of which are available to all as a special ability. And while one may aim and lock on to the target while Paused (ie; Myself), this does not mean one will be getting a head-shot result; abilities and weapon mods may be required for this effect.
ME3 allows every class to utilize any weapon, but each class has an encumbrance score that will affect powers, abilities, and thus weapon choices are made a key element. The N-7 armor may be assembled in any manner by the Player, but may not be as powerful as some complete sets available for purchase or rewards. If one cares about appearance, then a varied approach to the default is recommended; otherwise buy a set and enjoy.
The worst part of the game may be the long cut-scenes one may have to endure. Many are entertaining, but after a score of campaigns, the desire to rush through them intensifies. Sadly, there are also some interrupts; some of which seem less effective than skipping them, IMO.
However, the better part of the game are the unique Mission locations; if they are reused at some point, I missed it. And the Player gets the sense of non-linear gameplay even though it is a linear story (ie; much like KOTOR). And I am able to play all of the classes, which is a huge bonus considering the normal limits of a title associated with Action.