IMO UEFA, FIFA etc. aren't even the problem.
The clubs are. They're the ones that pick the players in those matches. They could easily use more of their U21 players and rotate more (would probably be better for youth development for them to get more time in first team games too!) but they don't. They only use them when first team players are out injured and then whinge about it.
"i'm not exactly keen on swapping out playing milan and dortmund for maccabi haifa and sheriff tiraspol"
That's like bitching about the FA Cup because Weymouth were in it (and got knocked out long before your team entered the competition).
Yeah, that's how superstitions work. People only talk about it if it "could" be true, not once it's proven to not be true.
Remember all the people talking about 2012 being the end of the world back in 2011/12? How many people talked about it in 2013? Or Y2K in '99 being forgotten about shortly afterwards.
Why would football superstitions be any different?
What makes a team like Brighton or West Ham so much bigger than teams like Wolves, Palace or Forest?
The whole ″big x″ idea is silly and outdated. Just let it die.
Why should they though? Why should the popular teams share their ticket revenue, sponsorships or merchandise sales?
That just discourages teams from actually investing in the team to improve.
Not to mention that'd would make it near impossible for promoted Serie B teams to compete and stay up.