Would anyone appreciate a Monster level up system?

It's just an idea dude. Don't have to bash it with a wooden club.

Buddy, you need to learn to not take things so personally. If you truly like your ideas, discover why they have been criticized and see if you can remold/salvage them to operate within the framework of the counterlogic provided by the critiques. Telling people to stop flaming makes it look like you had a passing thought and wanted to make it seem like it was super well-developed and fabulous by posting it as a thread on a big forum, but in the end it's just an idea and you don't want to feel hurt because a few people around the world don't like it.

You all day gets pretty boring. Wouldn't it be more better to have a mob that DOES something new every once in a while than just agro+ spam 1 animation for hours on end?

And this? 'scuse you, but some of us here did that all day till 200 and were able to deal with it. It's called a Netflix account, my friend.

Or how about level 200s going around committing suicides nonstop just to make mobs stronger?