I agreed w your whole post except this; I personally never got the whole 'fretted bass is better for tapping/slapping/metal/distorted' kinda mentality, I personally love slapping and tapping rounds, flats, or anything inbetween on fretless! I love the broad range of tastes that we all can have.
The tonal advantages of the fretted bass are intuitive, really, but to just state two of them: utterly precise, stable and repeatable intonation and the "muaah"-lessness of the note. Those are just facts about the tone of the fretted bass, particularly how easy and reliably you can get that kind of tone with literally no effort by the player other than getting that string mashed down against the fret at just the right time, and with the finger back behind the fret out of the way.
Yes, you can force that kind of "precision", pardon the pun, and tone out of the FL, with many years of hard work, a very high action and the strength of a gorilla, hard compression and ... well, you see where I'm going with this..
That's what I mean when I say the fretted bass is "better" for situations requiring that kind of synthetic/machine-like tone. Those are inherent tonal properties of the fretted bass, but the FL requires a lot of force to get the same thing out of it. You can hammer a nail with a crescent wrench, but a hammer is really the preferred way of doing that. The FL is not the right tool for that job is another way to put it.
Again, my goal here is only to tell the truth about the FL as best as I can render it, so guys aren't seduced into thinking the FL is something that it's actually not, or that the commitment to it will yield a result that it actually won't yield for them.
And finally, the idea that the FL is somehow a superior instrument that will make you a "better player" has a lot of myth around it too. I won't go into that here except to present myself as hard proof that that doesn't necessarily follow. I've played the FL for over 20 years now and I suck just as bad today as I sucked 20 years ago. And I fully expect to continue to suck going forward even as I continue to play the FL.
It is a brute fact that playing the FL will not improve your fretted playing as effectively as playing the fretted will. It will, however, make you a better FL player, but that's really all it will do....
L