Quick breakdown to why the negative reaction exists:
1 - Epic store lacks fundamental features currently.
2 - Their process of yanking as much as they can to be a store exclusive, sometimes weeks before it's due to for wide release (Metro for example) and grabbing Crowd Funded titles pitched and funded with multiple stores listed is an awful exercise. This is the biggest issue with Epic's storefront and these cases.
3 - The post the dev put out revealing the Epic store move was bad. If they had been sincere and showing empathic, not trying to say 'oh well worry about world hunger instead hehe' this wouldn't have been half as bad. Their interactions on Discord were also a mess.
4 - Don't throw insults at creators, but also don't throw insults at the core consumers you are trying to attract/sell to. Epic isn't the only storefront that seemingly does not understand who they are trying to sell to *taps nose*.
Sure, there's a toxic element to it where people are just wanting to be rude, and yes some die hard fan boys are in there, but the sheer level of 'but why do they not like Epic store?!!' is such a fake narrative. Anyone who has any level of connectivity with video game culture and consumer habits could have seen this coming a mile off.
The Epic store is great for devs/pubs, but they're doing an awful job of showing why it's good for consumers.