Well I don’t think it is just the battle scenes, probably it is a coincidence that the top 10 for Charizard all have the iconic Charizard vs Venusaur depictions. If you check the archive of polls, for almost all of the polls done, we consistently have had at least 1 modern artwork card in the top 5 or top 10.
I am not a big artwork person but I am of the belief that modern card arts are really something special. The ability to tell stories in just a single card beats out nostalgia, which is a very hard thing to do on E4 in my personal opinion. That is why the Battle Road promo which I stated missed on top 10 surprised me because I think the artwork conveys a lot of emotion (pain, anger etc) through that art and is really something special compared to other generic poses.
Maybe you will get your wish with Mega Evolutions in the future.
Cheers!