It’s less of a “for the battlepass” and more of a “Oh, that’s something fun I can do and be rewarded for doing.”
OW1 did this by giving you coins for playing underperforming roles and it worked. OW2 gives you the equivalent of a used tissue and some cough drop wrappers as a reward for doing the same thing.
Also, the quests do not have to be obnoxiously long just because they’re weeklies. 15 games of arcade mode was ridiculous for the old challenges without even considering the 10 minute queue time per match.