I still haven't played ME3 yet, don't really feel like it either. ME Andromeda will need some stellar reviews to convince me it went back to form instead of more cover based shooter.
I think that's a little unfair and that you should try ME3. Personally I also happen to slightly agree with your ending statement. ME2, while was a great game. It was my least favorite for that reason. Plus the more predictable narrative structure and a more accessible appeal.... I love it but it just wasn't up to par with ME1 and ME3 which both contain far more RPG elements. ME3 in terms of game mechanics really combines the best of elements of ME1 and ME2. There's days where I debate on which game is better, ME1 or ME3? Years later it's endless in my mind because they really go full circle with each other once the game ends. As for the ending.... all I can say is that it's your story and you need to make up your own mind. Never listen to others when it comes to the ending of the ME trilogy until after you've experienced the whole journey from beginning (ME1) to end (ME3). It really is an amazing and satisfying experience in my mind. Of course I recommend you do all the side quests and really explore the world of ME if you truly want to understand the ending. The theme is something that appears to be an underappreciated thing of beauty. Something so inspiring and powerful, but it's execution may have missed the mark by being a little... too ambiguous.
ME2 was indeed a bit disappointing after the first one. The main plot felt non existent and while some of the characters were interesting, the gameplay mechanics got old pretty fast for me. I played the demo for ME3, did not like it at all. Then the whole uproar over then ending broke out which also made it practically impossible to avoid major plot spoilers. Hearing it all leads up to some nonsense deus ex machina ending was the final straw.
Since then I have read the excellent Revelation space series, which I realized is what Mass Effect is pretty much based on. Except Alastair Reynolds' original version is so much better.
I loved the first game, so I'm not ruling Andromeda out just yet. But I'm very hesitant to get back into ME. Is it going to be another start of a disappointing trilogy, or maybe a great standalone game with a new original sci-fi story. I haven't followed it at all, so no clue.