The idea of Epic Store having exclusives doesn't bother me. On a conceptual level I get the objection but in this case all storefronts lead to my computer.The way I figure, if Epic Store keeps this up after it's become established, I'll be leery. At the moment, when it's still getting started, I'm willing to grant it some exclusives as a way to get the ball rolling, partly because getting Steam some competition is so important and at this point, it's hard to see how that could happen without some creative finangling like this.
On a more personal level... Well, I already have the account because I wanted to snatch up a few freebies, so in that sense there's no opportunity cost.
What bothers me is Epic Store is developing a trend of sniping games as exclusives on their store after the developers have already taken money on the basis that it's going to be available on Steam or GoG. That feels unethical to me and starting off with what feels like shady practices doesn't make me want to do business with them.