So you gret to Colonia in your jumper ship, and then want to do some mining, bounty hunting, exploration, but all those ships are back in the bubble....(And even for that exploration thingie, I feel like fleet carriers are just too slow. I can travel from the bubble to colonia in less than 2 hours. How long does it take for a fleet carrier to get there?)
You do exploration 50klys away from the bubble. Sure is nice to hand in explo and carto data in case of crash landing without having to return to the bubble.
Hmm emergency power cells needed but in a very restricted area. Load up my cutter with 784T and put them on my fleet carrier, along with H.E suits, Fruit & vegetables, Muon Imagers, Insulating Membranes, etc. etc. Then when I build something that needs 20 of them I can just get them off my FC without having to fly all over the place to source them every time.
Plenty of ways that an FC enriches gameplay. Absolutely necessary, no, but very useful, and therefore important, yes.