The whole issue of recycling guilds has already been discussed and a solution come up with, it's a matter of it being implemented (which won't happen until the entire guild system is redone because it's part of that).
The problem with the towering reward system right now is that it's made up of reward points that don't line up with most players' interests. No one wants to spend another 4k hours towering in the same guild just so they can get another hat, even if it's animated, when they can just get 4 other hats in 4 other 1k guilds. The whole thing needs to be balanced by a points system that allows each guild to decide what to spend their points on. You shouldn't be unlocking flat rewards at hour milestones, you should be getting a lump sum of points. Then, with those points, you can save them or spend them on what you want.
At that point, there's no reason to rinse-and-repeat in a new guild. You can just continue in the same guild and get the same reward over and over (probably with a cap) if that's what you want to do. On top of that, staying in the same guild or a guild simply existing for a period of time needs to be incentivized by points. I typed a damn 7-page PDF on how the whole thing should work, and it doesn't pertain to just towering.