Soft switches are fine if the power is really, really, low. For real.
Like, if the battery is rechargeable, 5-25uA is pretty much zero drain.
If it's disposable, you get about 1-5uA before it's A Problem(Because the only good use for a disposable is on stuff that only gets changed once in multiple years).
In a lot of cases the switch is the least reliable part, and it makes case design harder, and maybe compromises waterproofing.
Beware of alkaline cell leakage, though. They fare much better if they are isolated when not used for long periods. But you could use a low self discharge rechargeable cell like NiMH instead of alkaline, of course.
Like, if the battery is rechargeable, 5-25uA is pretty much zero drain.
If it's disposable, you get about 1-5uA before it's A Problem(Because the only good use for a disposable is on stuff that only gets changed once in multiple years).
In a lot of cases the switch is the least reliable part, and it makes case design harder, and maybe compromises waterproofing.