Many people have and are losing interest in the game.
Many people? Where did you get that information? Either way, people will inevitably lose interest in any game. Some will lose interest because they've been playing it for a long time, others will lose interest because of other games... That's nothing new, but just as some people are quitting, others are starting and loving the game. It's a business and that's exactly how it works. As long as Inno is attracting more players than that are leaving, or at least keeping the players at a steady number, they're doing a good job, they wouldn't be constantly developing the game otherwise.
Cheapening rewards? Take a look at rewards you could get a few years ago. They have actually been improving rewards, with practically each new building being more powerful and space efficient as the previous one.
Events and GBG? Don't do them if you don't like them, it's simple. A lot of players, especially those that were getting bored, like new features.
Constant glitches? Find me an online game as complex as this that doesn't have glitches. I'm not a programmer, but I can definitely imagine how much effort it takes to be working on a game like this. Of course there will be glitches.