It doesn’t affect your ability to play the game whatsoever, and this game COULD BE RUN LIKE EA RUNS THE GAMES. BUT games as a live service continue to cost money to keep going, so I support them fully on making a profit.
This skin also according to the bottom of their virtual ticket page :†The in-game items for Overwatch, StarCraft II, and StarCraft: Remastered will also be available separately in 2019—further details will be announced at a later date.
It won’t be locked forever behind a 50$ paywall, it will be either reduced in price as a single item you can buy, or given as an event challenge like the HoTS ones of the past or an in overwatch challenge like the nano cola one. Skins ARE in game content, but essentially they are only cosmetic completely optional and non game impacting content.
I think that is completely fair, and I think you just want something to be outraged about that 100% in the grand scheme of things DOES NOT MATTER.