The issue with size is less distance and more mission design.
Compare these two:
Both maps are 128x128 km with 16x16 gridsquares.
Vietnam in Air RB:

Smolensk in Air sim:

Do you see the difference?
Objectives.
Smolensk feels far larger with far less player density over vietnam despite being effectively the same map because…
On Vietnam, the greatest distance between 2 minibases is ~20 km (1 grid square)
On Smolensk, greatest distance between 2 mini bases on red is ~48 km. (3 grid squares, but slightly diagonal)
Greatest distance for 2 blue mini bases is sqrt((5x16)^2+(3*16)^2) = 93 km.
This alone makes the bombers spread out and thus spreads out people hunting the bombers, thus spreads out the people hunting the bomber hunters, thus less player density.
Beyond the mini bases, on Smolensk we just had an “Capture an A point” on B5, while red team had a bomber intercept on the D row (by the time I took the screenshot, the bombers were about to escape at D7, but even when they were on D5 it’s at least 16 to 32 km distance between people intercepting and people brawling for the capture).
There’s also ground targets to bomb at B4 and C5, this time being quite close together so not that big of a split.
Even on 64x64 (Ruhr) maps where a gridsquare is only 8x8 km, we get far greater distances between objectives:
Ignore the convoy objectives as nobody in a WW2 plane or even early-modern jet without guided munitions can kill them safely.
This is what I mean when I mean wanting bigger maps for air RB.
Bigger map as in: wider, more spread out.
And I’m pretty confident, at least amongst pre-BVR players, others mean the same but without the experience with other game modes to precisely define the issue.
Current air RB maps are narrow columns 16-48 km wide in a 16-32 km tall box where all 16v16 players funnel into in a chain reaction of base bombers/ground pounders, people wanting easy kills going after them and so forth. Having only 1 airfield excarbarates this funneling issue as people just fly straight at the enemy airfield even if they ignore the groundpounders.
The map itself is big. But like ~50 km on either side might as well not exist as nobody has any reason to go there.