I think he meant this in a different manner than you interpreted.
He didn't mean "Ignore people who made unpopular decision". Instead, look at the sort of decisions people tend to make, and use that as a road map for future styles of decision.
For example, let's say 90% of people side with Mages over Templar. So next time, they make a different story point, where you must choose between two groups of mages (to make the decision more difficult).
Or 90% of people take Companion A along. So when determining who would be a good cameo/returning companion, that character stands a greater chance.
The problem with that being that if they go that route and create a plotline where you have to choose between two factions of mages, based on the idea that a majority of people sided with mages in previous games, then there is the possibility that that will be streamlined into the main plot (and people who sided with the templars will be forced to pick between the two mage factions), or more focus will go into the mage faction plot (because, let's say, 95% of people sided with the mages) than any alternative quest for people who sided with the templars (let's just say 5% of the community).
I sort of see it as the same thing that happened with Mass Effect and Khalisah Al-jilani. In the first game you are interviewed by her and have the opportunity to end that interview by punching her. Most people did this. However there were other ways of ending that conversation - including one where you can turn her questions around, and make yourself look good at the expense of the council. It's shown by the way she treats you at the end of the interview, and confirmed by Hackett later on, that you've changed her opinion of you and she is now on your side.
In Mass Effect 2, however, regardless of your choice, she treats you as if you had punched her in the first game. (at least as far as I've experienced) This may have been a bug, however I don't remember ever hearing anyone discussing it.
There was also the subject of Morinth between ME2 and 3. Obviously a majority of players would choose Samara over her, as Samara was the first one you were introduced to. However, I remember many of those fans blatantly criticizing the fact that you even had a choice between the two of them. Unfortunately, even though I know that there were players out there who chose Morinth, very few said anything. Then when ME3 came out, all evidence that Morinth survived ME2 is erased, save for an (IMO rather touching) email at the start of the game; and a named Banshee at the end. Meanwhile, Samara is treated like any other ME2 exclusive party member.
There are many more instances of things like this, but I don't want to get too off topic. I understand that the ME series and the DA series were developed by different branches of Bioware - and I understand that it's difficult to keep track of all the different choices and consequences throughout an RPG series such as these. But my hope isn't that Bioware takes the information of the keep and says "Oh look, 99% of people chose this party member over this other one", or looks on the boards and goes "85% of people absolutely *hate* Anora"; and decides to devote more time and resources to create content specifically aimed at the 99%, or the 85%, and sweep everyone else (albeit, unintentionally) under the rug.
Quite the opposite, really. My hope is that they'll take the information of the Keep and say "Wow, I wasn't aware that you could romance Leliana, bring her on the Sacred Ashes quest, destroy the Sacred Ashes, *talk her down* when she threatens to attack you, and end the quest with her still in love with you... But 2% of our players apparently did this" and then make sure they don't create a quest down the line which supposes that if you destroyed the Ashes that Leliana "died".
So back to what you said earlier: I wouldn't *mind* a quest that allows you to choose between two mage factions, if you chose to side with the mages in previous games... as long as there was some sort of alternative. Such as a quest where you had to choose between two templar factions, if you sided with the templars in previous games.
I would *prefer* them to look at the information and say "hey, 5% of people sided with the templars, and only a small portion of them convinced Merill to join them. That's an interesting outcome. I wonder what Merill fighting alongside the Templars would look like. Let's make sure we don't have anything that automatically assumes Merill is dead if the player sided with the templars."