So long as non-western tech is automatically inferior to western tech both in tech progression and performance at a given tech level, I want to see more countries westernizing, not less.
If all tech group monarch point penalties are eliminated and other tech groups become competitive at the same tech level (no more "lol, i haz tercio, gonn' take over all Muslims nao") and maybe most of the tech rate penalties reduced, THEN you can complain about too many nations westernizing. As it stands, the penalties for being non-western are so harsh (Muslim? No new infantry for about 135 years, during which one of the biggest power jumps of any tech level happens to EVERYONE else's infantry. Sub-Saharan? Hope you like the harshest MP penalties in the game, crappy units, and having Spain and/or Portugal (or Yemen and/or the Mamluks) breathing down your neck in the first 50 years of the game. Mesoamerican and South American? Same thing, but maybe 100 years in. Anything but eastern or western? Doesn't matter if you keep your tech competitive into the late game, you're still not going to get new units while the Europeans units get exponentially more powerful).
If all tech group monarch point penalties are eliminated and other tech groups become competitive at the same tech level (no more "lol, i haz tercio, gonn' take over all Muslims nao") and maybe most of the tech rate penalties reduced, THEN you can complain about too many nations westernizing. As it stands, the penalties for being non-western are so harsh (Muslim? No new infantry for about 135 years, during which one of the biggest power jumps of any tech level happens to EVERYONE else's infantry. Sub-Saharan? Hope you like the harshest MP penalties in the game, crappy units, and having Spain and/or Portugal (or Yemen and/or the Mamluks) breathing down your neck in the first 50 years of the game. Mesoamerican and South American? Same thing, but maybe 100 years in. Anything but eastern or western? Doesn't matter if you keep your tech competitive into the late game, you're still not going to get new units while the Europeans units get exponentially more powerful).