Here's my reasoning for thinking they're a good idea for some games:

Overwatch. The first game was a paid boxed product and only had loot boxes for the recurrent monetization, but they could be earned for free by playing the game. The end result was that no-one bought the loot boxes so the game stopped generating income, which meant they couldn't justify making new content for the game.

When the game switched over to Overwatch 2 it also went free-to-play, removed the lootboxes and implemented a premium battlepass and direct-purchase store for cosmetics. This meant the game was now generating regular income that has allowed the devs to devote more resources to making new content and doing regular balance patches - which were the problems that caused Overwatch 1 to die off.

The unfortunate truth for live service games where new content is expected is that they need to generate recurrent income, can't expect the devs to work for free. I agree that for a paid boxed product paid battlepasses are rarely a good idea but for free-to-play games I think they're probably the best form of monetization when paired alongside a direct-purchase store.