Because there are people who want satanic/debased entertainment, and they don't see anything wrong with it; they are past all moral sense of sound judgement and sensibilities. We live in a world filled with depravity, with people who think good is bad and bad is good. The classic hero understands right from wrong, and does not devolve into barbarity; BW understands this about the ME franchise and they will stay true to it for the vast majority of fans around the world. Those who advocate for gore are sick in their minds and twisted in their souls - and they love it that way.
It is amazing to see quite a number of people who want ME to stop being ME. This has been often said by many others.
Yeah, it's super messed up. (hides her collection) I don't know what they're thinking. (drops it all over the floor) Uhh...
Seriously now, I don't think there's anything wrong with violence in fiction, especially when its more serious forms are restricted to appropriate titles. That means that not all titles should have hardcore violence for many different reasons - e.g. targeted audience, intended tone and atmosphere, etc. I'm rather indifferent to the idea of adding more violence, but then I also realise that Mass Effect in particular has never been crazy violent and thus I see no reason for it to go Saw on us.
As far as I'm concerned, I'd love to explore biotics some more. I'd be all over that. However, I don't know whether doing it this way would be a good idea. In a cutscene or two for good reasons? (E.g. The protag snaps under pressure and gets scary for a moment if, say, an interrupt is chosen.) Could be cool. Why not. However, in combat? Probably not unless it's quick and "painless". I see no purpose otherwise. (Especially given the reactions on this forum.) I think you generally want to be fast (Anybody who's ever got stuck in a finisher with some enemies around still alive will understand.) and there's no point in making it particularly morbid - as in, having fun with bending and twisting limbs - because our character's position will probably require them not to be a psycho. We also already have biotic explosions that tear people apart and allow us to slam them into the ground. That's fast and reasonable, yet violent.
I'd definitely build on what we already have that actually seems to work for most fans in this department instead of trying to deliver a different experience. Things like Doom may be popular, but they're popular for entirely different reasons than Mass Effect.
Either way, I wouldn't point fingers at people enjoying some pixel blood as long as that passion stays in games. You never know what's an individual's interest in it. Hell, in real life I catch spiders into jars at home so I can just release them outside instead of killing them, but in video games I will cackle at the scene where I can fry the goddamn batarian fixing the gunship during Garrus' recruitment mission because SCREW THOSE PIXELS THAT'S WHY.