It's always annoying when people bring up Planescape: Torment as an example why another game's writing is terrible. Planescape: Torment is perhaps the greatest written game ever made. It's analogous to saying X basketball player is **** compared to Michael Jordan. Tiresome comparison that tells you virtually nothing about the game to which it's being compared.
The argument annoys me even further than that as, and I write this as someone who loves Ps:T, that game also did have some serious flaws. For example, a lot of the really indepth choices were available if the PC poured a lot of points to WIS, INT and CHA, but there was no reward for players focusing on physical stats. The combat system and encounter designs were pretty horrid, the game was really, really short partially due to the complexity of the system and so forth. At times it even almost collapsed on that complexity, because it would build scenarios without really giving any payoff for them. And all of this ignoring that it also did use the AD&D system which was just horrid.
It is an awesome game and I would heartily recommend it to anyone, but the way it is elevated as the sign of perfection in discussions is always frustrating to me. Especially since it was a pretty big financial flop when it came out, so focusing on that model isn't exactly a sustainable business model.
It sounded like their plan was to make games before the original ME trilogy took place, but after polling discovered that fans (perhaps unsurprisingly) overwhelmingly wanted a sequel in some capacity. So the choice was either canonize an ending or Andromeda.
I'm personally very glad they are continuing the series, though I wouldn't have minded if ME3 was the last one. BioWare once had another sci-fi license that they decided not to make another sequel for: Knights of the Old Republic. I was pissed, but then their new project turned out to be Mass Effect, so that taught me about being close-minded.
I don't know, I am looking forward to MEA, even if I am nervous about the exploration focus, but I kind of have to respect the game developers deciding that this is a story we want to tell in this world and focusing on delivering that instead of trying to figure out a way to keep the world open for further games. I mean most of the choices in ME3 would be impossible to do if they wanted to keep the world open for sequels in the future.