Agreed. ME1 was ultimately the game that made me realize how much I disliked "traditional" RPG mechanics being applied to shooters. In a lot of ways, it was a really sloppy effort to drop weak RPG mechanics on top of weak shooter mechanics.
Deus Ex however had a completely different take on how an inventory should work - I wish more games (including ME) would follow in its foot-steps.
Stealth games in general are probably the best realization of an action RPG. They encourage roleplaying organically through level design and AI behavior rather than artificial stat progression and dialog boxes. The most recent Hitman, for example, let's me play an explosion-loving buffoon, a bloodthirsty hitman, an efficient assassin, or most anything in between. DX:HR is a bit less sandboxy, but generally contains a greater amount of reactivity as a result.
In fact, stealth games offer more player freedom in some areas of their design.
I was going to make a more in depth post about this before this thread had moved on to ammo mechanics. Essentially it boiled down to the way stealth games increase player freedom by offering a limited number of utilities that players can combine in different ways for vastly different results. This is in stark contrast to ME1's (and other ARPG's) philosophy of offering a large variety abilities with only a single specific use and giving the player a bunch of pointless skill progression. That method works, but doesn't scale nearly as well in an action context.
The inventory system, however, is something I believe needs to be overhauled in most RPG. Deus Ex and survival horror games have it right: limit our inventory to a reasonable size so we're forced to make critical decisions about our resources at hand. It may also discourage designers from making every RPG a scrounge-fest. The grid-based system might be a bit too much (though I like it because it turns inventory management into a mini-puzzle), but limited resources usually encourages more creative play.