I just don't recall hearing a single bowed string player (owning a $25,000 to $100,000 instrument) stating, "One of the things I like about this instrument is that it feels nice and sturdy."
It requires quite a bit more craftsmanship to build a very well put together thin-walled brass instrument vs. a thick-walled one. I would think that F. E. Olds "Ambassador" models would be the classic example of this. (The trumpet version of this particular model line was so cleverly designed that the bell and mouth pipe braces were built so that - even when they were broken loose from the instrument - they still were very resistant to actually breaking apart themselves.)
In the past - in my lifetime - the heaviest brass instruments were usually the entry level instruments. It was assumed that young inexperienced players would have accidents, and making instruments heavier and thicker would diminish the seriousness of the damage that they would do to those instruments.
Materials cost, but a tiny bit more material doesn't cost much more at all. Thinner walled brass sheet metal doesn't really cost much less than slightly thicker for some of the same reasons: the craftsmanship involved in making it that thin, yet without flaws.
Tactile experiences with brass instruments (such as feeling an instrument vibrate in one's hands) don't necessarily transfer to aural ones.
One of my instruments is handmade, the bows are thin walled, it's quite large (larger than any 6/4 c instrument) and features a very large bore with five rotors and all of the paddles and linkage that go with all of that. I appreciate the fact - what I'm playing it and when I'm picking it up to play it- that it weighs less than 24:lbs. - though I transport it in a protective case that weighs more than the instrument. (That having been said, I see most everyone carrying instruments almost as large as mine in cloth bags, with those instruments typically sporting quite a bit of denting and evidence of repairs... Though often - with exceptions - thicker walled than mine, knowing this from my experience in repairing all of those models.)
A much more commonly encountered thin walled tuba is the Yamaha 641 rotary tuba that is typically sold to schools. Those instruments are reasonably well made though I don't particularly enjoy playing them (which is related to their design, rather than their quality of construction). Being thin and located in schools, by the time I receive them for repairs, the damage is typically epic. The same is true for the old Czech instruments that are still in use in schools, but there's something about Czech design that defines that I'm usually able to straighten those out with fewer struggles and even without taking them apart.
For several decades now, American brass sousaphones have been built with very thin sheet metal, and arrive at my shop with epic dents, routinely. American fiberglass production has ceased, but ironically - before it was ceased - the fiberglass American instruments were made so thick and heavy (compared to those produced when I was in school) that (okay, I never have A/B'ed them on a scale to weigh them, but) I strongly suspect that the last of the production fiberglass American sousaphones weighed at least as much as the equivalent brass ones. (The Taiwan fiberglass sousaphones are also quite heavy.) One thing that I have found to be (odd/ironic/humorous?) about the very large model American sousaphone is that they have added a whole bunch of extra bracing to it - adding considerable weight, yet it is still made of very thin sheet metal these days (compared to Elkhart, Texas, and very early Ohio production.)
It's after 10:00 a.m., and this is all the time I have for trolling this morning.
