You don't need to worry too much about wedges for blast doors as you can fake it by insetting the door between a decorate wedged frame on both sides.
That's an "arched" door, not a curved door.
Rather like this:
On the other claw, This:
Is a "curved" door. note how it's literally 1/4 of a sphere? Where's the "door frame" trickery for that?
The extra blocks being requested would greatly assist any endeavor where a "curved/spheroidal" door is needed.
Mostly on "scale" or "to scale" replica builds.
Yes, there are a few reasons for using the "dated" blast-door. Chief among them: any server with "entity" limits for ships, each rail-door is an entity, as is each piece of a turret. I'd rather have the turrets, thanks.
Second reason: Combat resiliency! that rail-door likely won't have any shields, so a single weak swarmer getting past the PD blasts it off it's mounting, and then the server dies from collision checks.
But let's assume it just flies off, you've then lost part of your ship to an attack that would have been shrugged-off/ignored by a blast-door "door".
Third reason: sprucing up an older design. there's not enough room,
after fixing the power and weapons and thrust back to what they were meant to be, to install a rail-logic room for the rail-door.
As to your "blocks loading and unloading" thing. Yeah, that can sometimes be a problem on a toaster/potato PC.
Even then, it's only a problem when some douche built the entire hull of a 300~ish meter ship out of door,
and then sets it on a clock.
For the much more "normal" usage of a 30x30 shuttlebay/fighterbay/dronebay door, (or even a 40x20 I'm flexible) there isn't enough of a processing hit to worry about. Not even with 10 or so of them opening/closing at the same time.