Why the frak should I invest myself in another trilogy after what they did to the first one?
Retconning
Railroading
Rule of Cool>Continuity
Cinematics>Lore
Feelz>Everything
Why the frak should I invest myself in another Mass Effect game at all?
Exactly because we got so invested is the reason why you (and even me a bit) are afraid. Maybe I'm not alone in this, but I know when I got ME2 I was just expecting a fun ride. As ME1 and ME2 released, the anticipation and the expectations grew. Then. after following all the hype leading to ME3 (which I assume is the main point of issue for you), I'm sure we were all expecting this game to be Jesus incarnated in video game form (the over-hyping and not delivering on promises didn't help much either.)
I know ME3 had flaws. Heck, every game has. Maybe ME3 suffered from it more because of a lack of planning and expectations that rose to space (literally). Maybe the devs could've done more with extra development time, could've made some aspects of the game better, etc. Maybe it was just plain bad
But we have to remember what got us invested. That opening scene of ME1, that sense of awe and exploration. All of that potential is still there in that universe. You yourself proposed solutions to continue on with the franchise. There is still hope, more than you think.
And I can bet that after the ME3 fiasco, Bioware will be extra dedicated to making it right. Do you really think they'd make the same mistakes? Look at what the Dragon Age team has done after the DA2 fiasco. And the same seems to be happening with Mass Effect. Just look at what's been teased. The focus on exploration, story, and characters. What we saw potential in might finally be realized.
Nobody is forcing you to get back into the Mass Effect universe, and I have no idea what is in store for the next game tomorrow at E3. All I can say, is that you should give Bioware another chance and at least keep an interest in a game franchise that is, in my mind, the best of the best.