It’s hard to be a “fad” when Fender has been rolling their edges since the 1950s (then they stopped in the early 1980s on standard models... then began doing it again a few years later). It became a feature to note simply because it feels different. That’s not a marketing gimmick, it’s just basic spec info about the instrument - no different than stating the nut width or the fingerboard radius.
If rolled edges are pointless to you, cool. But it’s pretentious to assume that applies to everyone else, when there are so many different techniques to playing bass - some which benefit from this, and other techniques that don’t as much... especially considering everyone has different shape and size hands too.
Roasted necks also serve a purpose. The roasting process removes moisture and people started doing it in the first place to make the neck more stable and less likely to need seasonal adjustments. But even if roasting was just for looks only, that still wouldn’t be a gimmick, it’s just an option. Who doesn’t like options for any product?