Carriers aren't for everyone. They're for people who are playing at a rate that is far above average.
I get what you're saying, but speaking as someone who can afford a carrier, it's such an enormous game-changer that it's really in FDev's interest to make something similar available to most players.
the two "killer features" in my opinion are:
ability to move your entire fleet to wherever your interest in the galaxy moves
I've been playing since before it was possible to transfer ships. I used to have to buy a hauler, fly back, get my second ship, sell the hauler, then fly my second ship. Ship transfer was a game-changer. Moving your entire fleet on the carrier is a similar game changer.
off-ship cargo storage
I've been playing since before we had module storage. Adding that feature was a game-changer. Off-ship cargo storage is similar. It's more fun (for me, in my opinion) to have a dedicated miner, a small mining ship, that I can hop in for half an hour and hit a few cores, then store the cargo and do something else in the game. And sell the cargo later.
It's in FDev's interest to give mid-level players these two features. I agree with you that fleet carriers, as implemented, should remain an expensive thing for fewer players. But why not have a cheaper option too?
Why not have a cheaper carrier without the possibility of UC or bounties or even letting other people land on it? So long as you don't show it on the system map (a huge mistake in my opinion), why not give people that option?
A billion or so credits for a smaller, cheaper, shorter-range carrier with fewer available services. If it's not on the system map, what's the downside?