I have some experience playing bolt-on necks on steel strings, and they are fine. Instead of chopping your guitar apart after several years for a neck set, 20 seconds to take off the neck, them shim and put back together. Some traditionalists argue that the dovetail sounds better, but to my knowledge no one has ever been able to detect a difference. In fact, a well made bolt-on tends to have more contact between heel and body than a dovetail.
With Classics, the need for neck sets becomes more attenuated, but I see no reason that, for those eschewing the "Spanish Slipper" construction, a bolt-on would allow fine tuning the geometry of the neck/guitar.
That being said, I don't expect to see bolt-on classical necks for a while.
AND, there's something to be said for traditional lutherie.