Since I was one of those people, I suppose I'll defend my position. The difference between an ending that is ambiguous because the creator willed it so and one that is ambiguous because the creator ran out of time and just slapped whatever is indeed something that cannot be quantified and only by looking at each work specifically you can tell what is the case, although it is usually quite unambiguous which case it is. (Ha!) Personally, even if the FFVII ending was abrupt, Chris didn't argue that, he argued only that it was bad because it didn't 'explain everything', and the fact that the game earns this criticism does not mean this argument can be excused.Many comments reminded Chris that ambiguity is not necessarily a bad thing, such as the ending moment of Inception. But is the ambiguity of the FF VII ending appropriate? I would say it goes against the manner in which the rest of the story is conveyed, definitely.
Furthermore, I find the tendency of gamers in general to demand that everything be explained to be irksome and counter to our interests. Taking the ME3 example, there are two camps that embody this. Those that demand that the ending explain everything and refuse to come up with their own explanation, and those that flat out deny Indocrination Theory because they say Bioware has to say it's canon, which is just not how narrative analysis should work (if your theory fits the work, then it's a valid interpretation, the author be damned). These are small camps within the Retakers movement and not the reason why I dislike them, which is not what they demand but rather that they demand something at all, and more emblematic of a general endemic problem with gamers than with the ME3 brouhaha specifically.
To elaborate, there is a profound lack of symbolism and subtletly [http://www.rockpapershotgun.com/2012/04/03/its-time-for-games-to-offer-us-solid-food/] in games, and it arises, I feel, mostly from the idea devs have that gamers are dumb and that it's better to insult smart gamers to make sure the dumber ones get the story than to force people to think a little to understand stuff. Ever notice how every plot twist in a game is either telegraphed so hard your character has to be a complete moron not to realize what's going on or coming so out of the blue that there was no way you could have figured it out ahead of time? This is because devs can't do subtle, which is what you need for a good plot twist, and without subtle they either outright tell you what will happen or don't tell anything and the surprise falls flat. And this is the most basic of basic stuff; when you get to things like symbolism it gets even worse. What is the last time you saw actual symbolism in a game? The only recent, mainstream title to do that was Bioshock, in which an objectivist isolacionist society was symbolized by... an objectivist isolacionist society. Games never dare to make us read something between the lines because they hardly trust us to be able to read the lines themselves.
I find that to be a massive problem, and one of the ways gamers can help the industry to come out of this funk (other than the probably simpler solution of grabbing Gamemaker and making a game more subtle than the mainstream could dram of) is to show themselves to be able to decode things that aren't obvious. To jump in defense of the obvious and of the well explained as opposed to the ambiguous is anathema to what I think we should be doing. I personally haven't seen FFVII's ending, but from what is described the problem is not that it doesn't explain anything, but rather that it was jarring and left you unfilfilled. Why not identify that as the problem instead of phrasing your complaint in such a way that your problem appears to be that the game won't do your thinking for you?