I think the problem that Gears faces, is that it's MP simply isn't popular enough anymore to justify super long term support. And not, imo, because of any particular changes that TC has made, but simply because, by and large, people are kinda over Gears PvP. I know I, and many of my friends, fall into this category. We still enjoy Gears for the campaign, and we like playing some Horde now and again, but we haven't really been into the competitive MP since Gears 2/3. Mostly 2, really. And it's not that we really think it's gotten worse...I think we just don't really like cover based shooters as the basis of a PvP experience anymore. It's fine for PvE, because obviously enemies will always move out and about, so you get to always be shooting, and the action stays moving at a good pace...but in PvP everything slows down, and you tend to just wish there was more going on. Idk, maybe I'm wrong, but I suspect that this sentiment holds true for a lot of players.
Don't be surprised if TC makes some radical changes to Gears moving forward.