I couldn't be not against Wayland in those dark times when some distributions would make it as the default, at which time the flagship Wayland DE was using XWayland for its own panels. Which made a shitshow of a blurry mess on a HiDPI screen.
I couldn't be not against Wayland when in half of the applications I used clipboard wasn't working properly.
I couldn't be not against Wayland when screen sharing would either use X11 or not work at all.
I couldn't be not against Wayland when most of the complexity shifted from X server to compositors and toolkits, and it both diluted responsibility for the gnarliest bugs (go guess if it's the compositor or the toolkit! Added fun when it's the boundary of both!) and made it possible to write GNOME-only, or KDE-only, or wlroots-only software that won't work on another compositor because it needs a private implementation of an obscure protocol.
I couldn't be not against Wayland when your window manager breaking would bring your whole session down, complete with the breakage happening a lot.
I hear that there are problems with input protocols like "your toolkit has to implement several versions of the same thing and they all are half-arsed anyway", but living in the happy land of the Unicode's Basic Multilingual Plane, I know too little of this problem to have a say about it. But I'm somehow not surprised.
There is also this thing about Unix-like systems not being limited to Linux, and the story of Wayland elsewhere is way worse.
Most of the gnarliest points are now addressed, and Plasma got super stable around 5.26 onwards, however, I'm not really happy that we now have a triumvirate of Mutter, KWin, and wlroots, and that the bar for entry for new compositors is quite high. The fact that X11 allowed a proliferation of window managers is its advantage, not the other way around.
I'm wondering if someone gets to write a compositor that will be "engine, not policy" for Wayland, on top of which different desktop environments could be built. Like wlroots, but some steps further. It will probably have a year of glory, and then Wayland will be declared obsolete, crufty, insecure, legacy, and in dire need of being replaced with something lean and simple, and maybe written by an LLM. Good thing I'm going to be too old or too dead to give a shit by the time it happens.