I really think the gym change was a bad one, and this is coming from a person who has never a pokemon in a gym for over a day more than twice, and who checks out only 10 or 20 coins at a time 95% of the time. I had a pokemon in 5 gyms ONCE, but that was short lived. I was contributing 0% to the stagnation.
I thought gym stagnation was bad in the sense that seeing the same gyms held by the same teams at level 10 just seemed, well, stagnant... And it would suck for people on the same team who could never get their Pokemon in certain gyms.
But I thought it was a good thing in the sense that it was a pretty valid reward for players who coordinated or played together to hold down a territory.
A huge part of my motivation to play and work my way up in strength was to have the luxury of being able to have a pokemon in a gym for a few days, and being able to get coins on days that I'm not actively doing something. (Because I typically couldn't play like that everyday) I really want to be able to buy more incubators... I envied people like BowieZ (my rival) who could regularly check out 400 coins (and tons of stardust) because of all of the gyms they had every day. I can only imagine that's on the extreme side. If I could have 5 pokemon stay in a gym for 2+ days, that would be awesome for me. It was an enticing goal to work for.
I don't really think I need to go over why I think the specific changes they made are bad, but here are some changes that I think would have been much better.
There was nothing wrong with the speed of building up gyms or taking them down before. There just needed to be more of a reward for someone who takes the time to take it down... Whether it's in more XP, some stardust, whatever.
They could have even made a daily bonus for lowering the level or prestige of a gym each day. Things like this would encourage people to actually spend more time taking down these gyms because it would actually be worth the time.
On the plus side, I hatched Snorlax for the first time a few days ago. 2 days ago as I walked to school (on a route where I normally take the bus), I came across a gym inside some grocery store. Trained it up 1 level, got sniped by a teammate, trained another level up, put my 2263 Snorlax on the top, and it's still there. Yay. Feels great to check out coins for a Pokemon that's rightfully held its place for this long.