Well, in the end it depends, how much money Epic is giving to the devs/publisher, so they go for the Epic Games Store instead of Steam and the overall sales in the end. If it doesn't work out for them, the next game of the developer will be back on Steam anyway. I get it, that some indie studios are going for the Epic Games Store, less products, maybe a prominent feature on the Store and not being a game between lots of others buried on Steam and of course the initial payment and lower share for Epic.
From a purely spoken customers perspective: they usually don't care about how much money a dev gets, they are missing achievements, forums, reviews, marketplace, chat/mp options in parts, steam workshop and other great stuff. So well...I can understand if players want to stick to Steam for the moment at least. On the other hand you have people that complain anyway, I mean just think back about the time that Steam actually launched and the pure hate for it. That hate is still around for Uplay, DRM complains, Linux users complaining anyway about everything all the time, etc. ;)
It get's kind of annoying to use Battle.net, Origin, Uplay, Steam, Epic Launcher, Bethesda, Wargaming, etc. you can also count Discord, which has a store front or Twitch with their free games and their own Launcher...which actually keeps me from claiming some of those free games.