Good subject
I don't think your question applies especially to "custom builders". In fact, it probably applies more specifically to Guru than just about anyone else. Most custom builders actually base their business model on offering the widest possible range of finishes, & usually the more "out there" the better. I'd go as far as to say the aesthetic choices & size options are the mainstay of the custom build sector.
Major drum manufacturers use veneers to give the impression of solid wood. In fact, many list 100% (insert species) as a selling feature in the belief that customers find value in it, & use the term "solid" to imply quality, whereas it usually refers to the ply construction being of a single species.
I completely get your point about natural finishes not standing out in a stage setting. There's no doubt that a high impact wrap will draw attention & look more spectacular under lighting than any natural finish.
The likes of Craviotto & ourselves are no more "custom" than any major manufacturer. We produce drum series just like anyone else. We both have a custom option (just as DW, Sonor, etc. do), but in our case, that never extends to finishes. Although we realise a natural finish isn't for everyone, & therefore limits our potential customer base, we have to stick to our principals.
We know that additional finish layers make a difference to how
our instruments sound. I'm not saying that's necessarily a negative difference, but the difference is certainly there. We spend a lot of time crafting instruments that are highly resonant, & with highly resonant instruments, it makes a difference. Sure, if you use thick ply shells, or hang half a ton of hardware on your shells, then a wrap or heavy poly coat won't affect performance. What makes me laugh is that many builders who claim they make highly resonant drums, are the same builders who claim a wrap doesn't affect the sound of their instruments. That's BS, pure & simple. You can't have it both ways. To those builders who doubt the correlation, I say this - what would happen if you wrapped an acoustic guitar? --- exactly! I'm not saying low resonance drums are a bad thing, quite the reverse actually, it's a totally valid approach to the instrument.
Anyhow, the moment we give in to fashion, or try to please the widest possible demographic, we're screwed. If customers place stage aesthetics high up their list of priorities, then there's a whole world of builders out there, both large & small, that will be only too pleased to satisfy their requirement. We concentrate on the sound of the instrument. The aesthetic is important to us too, but absolutely secondary to the performance of the instrument. In our case, that means putting nothing on the wood other than a very thin sealing coat of shellac & finishing with buffed layers of hard wax. We don't stain, simply because we believe in celebrating the beauty of the wood, & as we go to great lengths to select our woods, it's nice to put that care & attention on display.
We're missing out on a large section of drum buyers, we know that, but watering down our own principals is just something we're not prepared to do.