Personally, I've never considered PASSWORD_STORE_CLIP_TIME very useful, so my opinion on this might be irrelevant. Before I added --paste-once I used to clear it manually right after I pasted it, so I never ran into the timeout.
However I would assume that users who appreciate this feature wouldn't want it go away implicitly by enabling PASTE_ONCE. Scenario: enable PASTE_ONCE, but don't actually paste because you got something else to do, will remain in clipboard "forever" and might be pasted unintentionally somewhere else.
