What the hell does this have to do with user experience?
Dev experience? Compared to what exactly? You have 10 hello world windows floating around or what are you talking about?
X11 and the whole desktop linux world is a huge vulnerability, not letting a random install script/dev tool become trivially a keylogger is not security theater. vsync is not mandatory, you know that right? It can be controlled by an app, e.g. games can control it themselves. Outside of that, why would you want tearing?!
Worse performance? Is that why embedded systems actually prefer wayland solutions over literally embedding a huge monolith? It has as many functionality as you implement..
I’m fairly sure that a bug in xserver will bring down the whole system. There is nothing inherent in wayland demanding a monolithic approach, you can have a server maintaining connections to clients and a plugin that handles the window management part that can be restarted.
You managed to not have a single valid point, congrats!
Avoiding tearing inevitably involves adding latency (the data is ready, render half a frame now or wait for vsync?) Some might consider it worthwhile to give up frame-perfection in exchange for getting as much data to the user as fast as possible; that's valid. Latency isn't just important for games, it colors every interaction we have with the computer.
That's less and less relevant as GPUs and displays get faster. You might gain a trivial amount of latency in certain cases, with specific apps, at the cost of bringing back stuttering. The normal case is always going to be vsync. If your program is hardware accelerated it's not actually rendering "half frames," it draws the whole frame and the tearing you see is just a result of swapping at the wrong time.
What I mean here is the rendering in clients isn't going to change either way, everything is already built to use vsync. Turning it off is more a matter of how many switches the compositor wants to provide for controlling the throttle. Most compositors should have support for fullscreen unredirect anyway, and that gets you most of the way there.
