While this debate will never end, mainly because people seemingly can't understand how other people can like something different, I will say that I personally feel like the "retail crowd" as you've dubbed them are far more toxic in what they're saying.
The main arguments that I've seen being spouted over and over again are "IT'S JUST NOSTALGIA, STOP ENJOYING THINGS" and the opposite being "CLASSIC WILL KILL RETAIL".
Neither is obviously logical to any sane person, but there's a large difference in what's actually being said.
"Classic will kill retail" is a jab towards retail as a product, belittling or ridiculing the current state of the game.
"IT'S JUST NOSTALGIA, STOP ENJOYING THINGS" is outright belittling a person and their opinion.
I personally find the "it's just nostalgia" crowd to be a lot more toxic and petty than the other "side", but maybe that's just me.
Either way it's hard to tell the success of Classic yet, but seeing how popular OSRS is, there's clearly a market for older versions of the game.