The community behaves like children often largely because a huge majority of it are basically (mental and physical) children. There are some of us who are mature adults with sensible minds that understand logic and how the world works, but most working adults who are of such a mind simply don't care about a jailbreak are are far more concerned with having a stable, secure, properly operating device. And since the very nature of a jailbreak means a wildly insecure device, it's something that they are largely uninterested in.

Outside of a minority of us, the jailbreak community is largely made of children who want cool icons or to fuck with things to the point their phone barely runs or their batteries die after an hour and a half so they can come on here and complain about their shitty iPhone crashing and boot looping and all that. They feel entitled. They want everything they want and expect everything to work how they want. They don't understand risk, they don't understand how things work, they don't understand that jailbreak devs work for free and on their own time, and often give things to the community that they COULD sell to Apple and make a killing off of. They bite the hand that feeds/may one day decide to feed them because they don't understand anything and just want what they want when they want it.

That said, some of these developers do the community and themselves no favors. Teasing children makes them annoying as fuck. They already feel entitled, and it just sends them over the edge and makes the place toxic. In turn, it makes other developers or potential developers want to stay as far away as they can.

On the note of Apple taking tweaks, to be fair, the vast majority of tweak developers simply take ideas from other people, other operating systems, etc. themselves. Very few come up with anything unique, so I'm not prepared to really call Apple out on that. People imitate/copy what works and what seems like a good idea. It's not new to this industry, or any other. In fact I kind of appreciate it. They've largely gotten the most important parts of a jailbreak (for me) into iOS stock. Which makes it so I have to deal with these idiots far less often (though thanks to iBlacklist and a few other things, I miss jailbreaking.)