I think you are misinterpreting many posts from others. I can't speak for everyone but I don't think there's many who don't still enjoy visiting. It's like watching a family member you love and care about quitting their job, piling on 5 stone and drinking heavier every night. You still love them and enjoy their company, but you find their gradual decline sad and regrettable.
As for your points, they've done very little to address cosmetic maintenance over the last 20 years so why would they do anything about it now? Some areas of the park have not been touched since they were built and quite obvious issues have been left untouched for years. Yeah, if you look hard around Europa or any park you will find issues. The problem is with AT, you don't have to look hard at all, it's in your face as soon as you walk into the monorail station. Any TLC done last off season was just a drop in the ocean, not even the bare minimum amount of work the park needs. The frustrating thing is, some things are such cheap and simple fixes/cleaning that you have to wonder what the blocker is to sorting them out. Lack of care? Not seeing things from a guests point of view? For example, I'll let you know if that hat that's been there for weeks on the roof of the vending machine shelter in the Galactica queue is still there on Thursday.
It doesn't matter when kids reach 1.2mtrs in height, there's very few attractions in the park the whole family can enjoy together. Instead of rectifying this, Merlin made the decision to turn one of these rides into an upcharge horror Dungeon and run the Rapids and Duel into the ground. Trust me, I've been taking a family of various ages and heights to Towers for years and there's no other park of it's size like it. It's a ball ache, loads of splitting up, waiting around and finding things to do in a specific area whilst some of your party does something they really wanted to do that the others can't. It's a very secular park when you're there with a family. It's not just the number of attractions between baby rides and thrill, it's the types of attractions they are and where they are located in the park.
There's loads they can do about the Monorail throughput problem (loads they can do about the dreadful, filthy state of it as well). They could install air gates, a cheaper manual alternative, or my personal favourite, supervise guests on the platform and let them wait there like at almost every other train station in the entire country.
When considering dark rides, 3 isn't particularly a lot for a park the size of Towers in a country where it rains alot. Last season this number was a measly 2. 1 of those is fine but small. 1 is really only suitable for older kids and adults. The other is like riding through a primary school art project.