Virt, I don't know what to tell you.
Last Friday night on Mirage I ran a Partisan B (quad LBX5) and handily knocked 4 Sullas out of the air and 3 Hawkmoths before switching over to another asset.
Later on I bought a Huit Prime and trashed a Shiva pilot twice in a row as he was trying to line up on me for a firebomb drop. About 6 seconds of concentrated fire at his body and he exploded. You can confirm this in the editor if you like.
There are several other assets in the game that are extremely effective at bringing down aeros and VTOLs. The RAC2 Uziel variant is absolute murder on aerospace when it is crouched. The same is true for the RAC5/UAC2 Hollander. Both of these 'Mechs are relatively cheap AND have a +6 degree bonus elevation by default for use against airborne assets.
As I have already stated in numerous other places, additional balance to the aerospace role will be done via changes to supporting mechanics like repair cost, repair time, rearmament method, damage reward, redistribution of aero armour values and possibly small weapon modifiers. We are also introducing new assets that will be specifically used in an anti-air role which should lend themselves to being much easier to balance. Right now one of our balance challenges is that "AA weapons" can also be used against ground targets.
We will get there, you just have to be patient and trust that we know what we are doing. Creating numerous threads/responses around the topic won't make it any happen any faster.