As people who love aesthetics of chips, cards, tables, lighting, everything, its no wonder they've grown attached to the suits being their given colors. I actually just ordered my first 4 color deck this morning so we'll see if it changes my mind, curiosity got the best of me.
My rational argument is one of aesthetics and teaching practicality: I love the red and black, always have, and I think the blue and green look light and silly in pictures. Im sure they're helpful for some people but Im young and so are the majority of my players, jumbo index is more than enough.
I would also be afraid of the opposite occuring: I teach lots of new people, if I teach them on a 4 color will it mess them up on nights here or there where someones using a 2 color deck(vast majority of them)? I cant have them leaving and taking it for granted that all reds are hearts after a couple beers lol. If Im teaching awareness Id much rather teach on 2 color.