Entirely possible that the original design was discarded because it was worse than what we have today.Gameplay wise I strongly suspect what we have now is a lot better than an "exploration" or "mining" FC variant would be, which would probably have come with a static set of services enabled, including of course some outfitting and shipyard packs of minimal use to most players. The ability to set up your own carrier loadout and only have the bits you actually want is probably far more important than having a nice-looking support ship hanging around it.
It's just that when they mentioned support vessels, I was imagining at the time they could be used to refuel carriers, or probe gas giants, or auto-mine rings, or automate hauling to/from a station without having to do it yourself. Or that you, the player, could actually operate them yourself (i.e. them being new ships with bespoke functionality), with potentially new gameplay loops. Back then I used to dream bigger for sure - so the actual FC release was a disappointment (classic case of not tempering expectations), even though I still enjoyed them (and the emergent gameplay, Borann et al) at the time.