Hi SO, yes as I understand it for acoustics the main resonant plane is the front wood. You pluck the string and the bridge converts the vibrating string into a vibrating wood top. The back and sides do resonate a little but the top is where the action is AFAIK.
I've not heard of Ovation's having any trouble, plastic is a very stable substance. What the wood is doing is flexing and it get's better at flexing in the right way the more it does so. Plastic also flexes very well but I don't know if it improves over time.
<and that if the guitar wasn't played, the wood would "deaden." > Many thanks Jerome this is a bit of the jigsaw I'd not heard before, I assumed that once a guitar had been 'worn in' it would stay that way, but I can see that unplayed the wood might start to stiffen up.
This playing-in principle applies to acoustics with solid wood tops but not those which use plywood (I suspect these won't improve because the glue and crosswise grains in the laminate is too tough/stable) and electric jazz guitars (often called archtops) since these have flexing tops. It doesn't apply to solid body electrics and semi-hollow electrics. I am not sure how the middle ground of semis with central blocks will figure, I suspect alot is in construction and glueing, so a Gretsch 6120 will improve but a Gibson 335 won't, generally... if they're the regular types...
I'm off to exercise my Seagull now, I've been neglecting it recently...