I think it's the very idea that both Mass Effect's and Gears of War's combat is cover-based shooting, so chest-high walls of some design are involved by default. Gears of War, however, doesn't have the liberty of using RPG mechanics such as latent spellcasting to mix things up, so combat in Mass Effect comes off as slightly more flexible than being forced to take pot-shots from behind cover until the other man falls down.
All this being said, things like blindfire and dodging/rolling are things that I'd generally consider to be a welcome addition to Mass Effect. They're not humongous innovations to third-person shooters, but established mechanics that would most definitely improve the shootery side of 3. And while Gears of War doesn't really have the most inviting palette design, there are enough changes in environment to spice things up a little, as opposed to the repeated dungeon crawling and corridors-with-flanking-opportunities in Mass Effect 1 and 2.