Let me preface things by saying that this is neither a scientific paper nor a definitive answer. It’s simply a slice of wholegrain common sense, a meaty layer of builder knowledge, with a dollop of full-fat player experience. To this end, I’ve conscripted music industry friends with bags of the aforementioned to help guide me through the shark-infested waters of opinion.
There does seem to be something of an obsession with lighter guitars, though. Ever noticed how many guitar store websites have photos of high-end instruments on scales, so you can see how heavy they are? In my experience lighter guitars do sound different from heavier ones. Consider an 8lb Les Paul versus an 11lb monster. The lighter one is likely to be more responsive: tickle the strings and it mews like a kitten; whack it hard and it roars like a tiger. The hefty one will be more of a bruiser, with less dynamic response but more midrange grunt. And many players believe that’s what a Les Paul shouldsound like.