Inquisition sold well. And was actually rated well too, its just that it had the misfortune of being released only a few months before Witcher 3, which completely eclipsed it in every imaginable way. A similar thing happened to an old game called "Shogo: Mobile Division". Damned good game, very advanced for its time, would have gone on to win multiple awards, but it had the disgrace of being released at the same time as Half-Life 1, which swept the world by the balls, won every award, and left Shogo to languish in obscurity.
When compared side-by-side, Half-Life is obviously MUCH better than Shogo, but when rating Shogo by itself, it was actually a pretty good game for its time, and had it not have the misfortune of being released next to such a strong rival, it would have built itself a much higher fanbase.
The exact same thing happened to Inquisition. Its not the best bioware game, but its WAY far from the worst. People just rate it poorly because it was side-by-side to Witcher 3, one of hte most acclaimed games of all times.