Wait, I'm not done being ticked off. I'm pretty sure I'm going to have to start an email campaign or something. Surely Bioware would put a stop to this... if money hungry EA wasn't their new lord and master.
Alright, now let's break down a few (a very small percentage) of the reasons this won't work.
Shepard's character is malleable and personalized to the player. No writer can show every aspect of that without making the him seem insane.
The universe of Mass Effect takes pages and pages, hours and hours to create and flesh out. You can't do that within the time frame of a movie.
Ensemble Cast is a vital part of Mass Effect, something Hollywood routinely screws up. Sure, Seth Green can actually play Joker. But if you screw up or marginalize even one character, you destroy the story. For instance, you make Halle Barry Storm in the Xmen. Or in Mass Effect, you make Meagan Fox into Ashley Williams. Same problem. She's a celebrity, she's popular right now. Cram her in anywhere she fits. Damn you and your committee-based casting Hollywood!
Effects. The SFX in Mass Effect, done right, would cost more than Avatar. Your alternative is atmosphere destroying cheap CGI.
Racism. Racism is a very real part of Mass Effect, but Hollywood has rarely, if ever, handled racism deftly. Sure, the occasional movie gets it right, but its hardly universal. And you thought Fox News' Sexbox - Mass Effect Porn story was bad? Wait till Hollywood mishandles the racism and suddenly: Video Games turn kids into racists.
I could keep ranting, and its tempting to do so. But I try not to post more than three times in a thread.