Is there a perception that an Epic key is a lower value product than a Steam key to some people: sure.
Is Epic 100% prepared to eat that bit of internet rage? Yes. Honestly, there’s no way they didn’t know that paid exclusivity deals was going to ruffle some feathers. It’s a calculated move that is absolutely going to pay off for them. It’s probably the only way that a new distribution system is going to get a critical mass of customers. Sure, Fortnight is huge, there are limitations to that audience in converting to customers of other games.
Look how long it took EA/Origin to get a decent backlog of third party titles, and they did that by taking nearly all of their titles exclusive. That was annoying then too, and people still hate on Origin, but I don’t think anyone thinks EA’s PC business is failing.
Epic doesn’t have the luxury of EA’s catalog of games. Throwing out bags of cash to give out free games, and paid exclusives is doing exactly what they want getting their storefront on more computers, and increasing their customer base to the point where eventually, the store will provide a recurring revenue source for Epic.
Internet rage is pretty weak. It blows over as soon as people want something. Battlefield games and Calls of Duty still sell fine. Yes, it helped tank Star Wars Battlefront II, but that was an issue with the game itself, not the experience of buying or installing the game.