the battle pass stuff definitely seems like its aimed at whales, depending on how often they release a "season". If its 60-90 days like most modern MTX games then i can see a lot of people just "buying" their way to the end and getting all the cosmetics, which is probably their design goal. Its definitely the most boring and uninspired aspect of the game, just a tiny step above grinding loot cave in destiny. Dailies, Weeklies, having to do it for each different character (will be CRAZY when there are 15+ characters) to level 40, etc. I did hit level 5 (battle pass, not character level) on Kamala after just like 8 hours so far so its not too awful but its completely hours or money = levels.
Its probably the grindiest battlepass I can think of, maybe dota or something exceeds it but not Fortnite, COD, Rainbow Six, etc. and i'd bet those games are way more fun multiplayer.
I'm really enjoying the SP campaign, but its a 10-15 hour game to 100% that. I don't want to prejudge but based on the combat and loot and everything I just can't imagine multiplayer being that compelling past a few days.