If not overly manipulative or overly forced on the player, they can be a fun bonus for the game. Overwatch 1 comes to mind as an example, and War Thunder's battlepass missions are sometimes good.That said, it should be basically offering an alternative approach to playing, rather than the more abusive, "Log in daily and grind for 8 hours" that is so common. "Play 3 arcade mode games for a free skin" is encouraging you to take a break from comp and try a more casual mode. Its a great way to reward less serious play. "Kill 3 enemies with small, medium, and large caliber guns for a new decal." encourages trying new equipment and playing off-meta equipment. Theres lots of boons for this sort of content (if implemented well), regardless of the monitization.
Edit: To put it another way, players optimize the fun out of games - examples could be playing only the meta, or taking the game way too seriously. Good battlepasses and missions encourage trying other ways to play for variety or for fun.
The whole point of what I said was that it shouldn't be an incentive to play the game, it should be an incentive to try new things within the game that you already enjoy, should you chose to.
For example, me and my friend group put 1000+ hours into CS:GO. Almost all of this was in competitve because that is the mode the game is built around and the mode that is considered the "real" game. At the same time, playing the same game day after day, while enjoyable, is also repetitve. When operations (battlepasses with missions) began, we'd organize to complete those tasks as well as playing normal comp. Most only took 15-20 minutes and while the games were less refined, they were still fun and injected some variety into our otherwise repetitive gameplay. The game as a whole was made more fun because the tasks convinced people to leave the better gamemode in favour of adding variety. At the same time, not all of us completed all the tasks, and not all of them were needed for all the battlepass rewards. It was just a way to encourage exploring other parts of the game you might not have touched since you learned the meta, or found your favorite gamemode.