I'd say it's a mixed bag on either front.
On one hand, I'm all for being able to change out basic items on the things I own. Who doesn't what to be able to take care of their own stuff?
On the other hand, from phones to tablets or even laptops, I've found that around the time I need to replace a battery, said device ends up losing manufacturer OS support in another 12-18 months or something else that's age-related goes out. I've had that happen multiple times now and ended up thinking I would've been better off putting the money into a newer device. I know that's playing into the whole planned obsolescence strategy but when I'd already gotten, 5-7 or more, years out of a mobile device I'm thinking that isn't too bad. However, that brings up another point. I think if more people were able to put off upgrading for longer periods of time that would cut down on waste far more than being able to swap a battery. I think the exception would be a defective battery which ought to be covered by a warranty anyway since most seem to last for quite a while these days.