Maybe the more expensive the guitar, the more difficult is is to change batteries.

My cheapo electro-acoustic has the 9v PP3 battery in a compartment set into the side of the guitar (i.e. on top in the playing position) and it can be swapped out dead easily. Looks bloody awful though, and probably affects the sound.

Whereas the battery in my most expensive acoustic fitted with an under saddle pickup is a bugger to change, being very inaccessible inside the body.

My 'medium' workhorse (somewhere in the middle, price-wise) has a detachable Fishman pickup so that makes it easy :)

I hate those snap-on terminals though - have you ever broken a battery or the connector by trying to prise them off? I have (luckily not in a guitar, though - yet) :-(