> simply unused most of the time
That's an assumption that is only true if you are careful to only use Gnome/KDE style, recently made applications. Backwards compatability is a good thing, and most of those features are necessary for running older software, and they don't interfere with modern software.
> nobody uses bitmap fonts
I use bitmap fonts for almost everything that isn't firefox and ps/pdf rendering.
$ xlsfonts -1 | wc -l
16264
Bitmap fonts render significantly faster, and a well made bitmap font[1] that was actually designed around pixels avoids anti-aliasing which saves CPU and occasional rendering issues[4].
> everybody renders into pixel buffers anyway
GTK+ and Qt render into pixmaps. Other toolkits vary.
> because the protocol demands it
...because backwards compatibility demands it. Maybe you only run recent software, but that isn't always an option.
> protocol being horribly outdated
Fortunately X11 has an extension mechanism which allowed new protocols to be added at runtime, removing the need to use older protocols. This is needed if compatibility is to be maintained. Unfortunately, the fd.o culture seems to think it's fine to remove working code without regard to the people that do use it.
> Wayland as far a I know is also a much simpler concept.
It's simpler because it's feature incomplete. These features still need to exist, and all Wayland is doing is pushing those problems to other areas where they are someone else's problem. In some cases (like use cases outside their experience), Wayland developers like to pretend these problems don't exist.
> I would tend to Rust here
I completely agree that Rust is probably a good choice, as it was designed specifically to avoid many common types of bugs. C is good, but Rust may be the first language that can actually replace it.
[1] Such as Terminus[2], Dina[3]
[2] http://terminus-font.sourceforge.net/
[3] https://www.donationcoder.com/Software/Jibz/Dina/
[4] http://www.antigrain.com/research/font_rasterization/index.h...