Your last comment is a true statement but it isn't an argument. Just because X11 was done in the age of terminals and before gpus existed doesn't seem to support your point unless "old = bad" in your view. I understand how type systems can help, some patterns are good, but some of those ideas existed before X11 actually, so no period of time has a monopoly on good ideas.
This is ridiculous. Maybe that's applicable in a very short timescale, but definitely not to the protocol which appeared in 1984.
There is a thing called progress, people invent quite a lot through the years: type systems, patterns, design ideas. Not to mention that hardware has changed quite a lot through the years: X11 was done in the age of terminals and absence of hardware acceleration.