Part of me does agree with you, especially about the balancing and characters in Mass Effect 1. I can't really comment on the 'gameplay' side of any of this because I never care about gameplay anyway and playing Shepard as just a straight up soldier is good enough for me.
So story is my only angle whenever I talk about Mass Effect in general.
I certainly agree with your assessment of the character of Ashley Williams. Her development over the story that could be central to her character (if you the player get involved with it) and it's true, her character really is tragically misunderstood by the majority of players. She's seriously got to be one of my favorite characters in gaming, let alone Mass Effect for just that reason that she was an almost perfect recreation of a human being, flaws and all. It's funny though, people complain about the lack of flawed humanized characters in games then complain that the ones they get aren't likeable.
I also think the romances were much to shallow, and plus given that they ran out of things to say if you didn't romance them, that's a total of six out of the original ten squad members running out of things to talk about the second 'boning' is no longer on the menu. I dunno, in Mass Effect 1 they just felt better. Especially the Ashley one given that it can literally get started in even the earliest parts of the game, you didn't have to wait for a loyalty mission to be able to romance her.
Also, the fact that the majority of the game is spent doing loyalty missions meant that the actual story (stop the Collectors) felt like it was being pushed to the side. I mean you need at least eight missions to recruit all the original team then another ten to get all their loyalties. None of which have any bearing whatsoever to the main plot, with the obvious exception of Legion's 'recruitment'. The fact that I literally spent more time fighting random anyonymous mercs then I did fight Collectors made the whole idea of them being the galaxies new 'big bads' ultimatley laughable.
Also, why did almosy EVERY SINGLE LOYALTY MISSION have to be a gunfight? They got really tiresome really fast and after a while I just slipped into a trance, with only Samara's and Thane's really sticking out as significant. Well, also Grunt's because it meant I got to hang out with Wrex again but still...
Everything about the Mass Effect 2 story felt like just filler. Like between the defeat of Sovereign and the Return of the Reapers, Commander Shepard just potters around for twenty odd hours.
For what its worth, the gameplay was fun (not that I cared) the graphics were great and the characters were well imagined and thoughtfully fleshed out (even if my two favorites from the last game Ashley and Wrex are absent from the team) and there's no denying that the final mission gives me a chill and goosebumps every time.
Even if I ultimatley didn't want to romance anyone (I will win Ashley's heart back damn it) and found the story pacing to be a bit off at times I still admit I had fun with it. Mass Effect 2 is a great, well polished game.
However, it was Mass Effect 1 that I fell in love with in the first place, and like it or not, Mass Effect 2 just lacks the original's charm in some places.
Partly by cramming in a way too huge cast, partly by abandoning the beautiful and vibrant colorful world for a dark angsty one and partly by pushing to the side two characters I absolutely fell in love with (Wrex and Ash, one was my badass and one was my love interest... see if you can guess which was which).
So ultimatley, for nostalgia's sake I still got to go with Mass Effect 1. Sure it wasn't as polished, but I played that game at least twenty times. I've only played through Mass Effect 2 twice, and I haven't even gotten any of the DLC's.