Jamerson's strings were dead-dead-dead. He stuffed foam-rubber into the bridge-cover. He did a lot of "preparation" to get that "Motown sound." Why do you think it is HIM comes to mind when you think of "that sound?"
When I think "P-bass," I think "slap/pop."
Now, if you have a FRETLESS P-bass with Jazz flats on it, you're going to have a far different "tone" than you have with fretted and roundwound strings. So talking about "that Fender tone" is kind of pointless, IMO.
I dunno...Jamerson was one of the original Funk Brothers from about '59 or so. He played on so many of the great Motown classics that I just associate HIM with that Hook on the Precision.
I guess it's all about your frame of reference. As I said, I don't play any slap/pop. Aside from Flea, I really don't listen to much of that style. So you may be right about the P-bass being great for that style with rounds. In fact, there probably isn't a bass that's used across a wider range of styles then the Fender Precision Bass.
Obviously, tone has every bit as much to do with the player as it does the instrument. So being that I use my P for Motown and don't slap, that's my genre of reference, and talking about "that Fender tone" is not so pointless.

