Those Rogers sets I mentioned...... there is nothing to mod. They were perfection 50 years ago. They are today.
So mods..... there is a huge vintage parts market flowered up on ebay over the past several years. Some pretty sad condition drums dismantled and parted out have been seen. And then, there have been some pristine, nearly, if not absolutely yes, collector grade quality sets dismantled and parted out down to the last nut, bolt, and washer. Drum strippers are a thriving business. The only known example of a Rogers 1960s Powertone ALUMINUM shell snare drum was stripped for parts by one of these sellers. I really do believe some drums ought to be sacred from modification due to their historical import. I have seen at least one fake Dyna-Sonic snare drum for sale, assembled from parts stripped from other drums, by one of those same sellers. And that would be the same seller who had nearly a half dozen "pristine" and very rare Rogers 1960s Dyna-Sonic snare drums for sale. So I guess the answer to the question of endangered species, is fastly becoming a "Yes!" How do you trust the originality of a collector grade piece from a disreputable source? And unless a buyer can do an "in person" disassembly of a drum, there is no way to really know if the parts on the drum are indeed original to the drum, and even then, it is impossible to say with surety these parts came with this drum. So you get the drums that are parted up rather than parted out, and they get sold to people who want that drum in that color and now it is in the open market and the drum is forever tainted because it has been "modded" in such a way as cannot be seen. Along comes someone who wants the drum for what it is, who really knows what it was, and suddenly that 3000 dollar collector piece is no longer the collector piece it was. The overall real danger with those kind of mods is to destroy the value of the drums in the hands of honest people.
I agree with the OP, that some mods are necessary to some drums to make a drum perform. I also think some mods are barely an alternative to a bottle of lighter fluid and a match.