In order to fixed the AA targeting issue the game would have to be radically redone. Essentially both aircraft health and AA dps would need to be cut by a massive factor such that AA installations have such pathetic dps to be not worth using. That would also enhance air diving interactions (flex AA actually does something), and allow for gunships to have a niche (semi-resistant to AA but vulnerable to flex AA). But I think that the dedicated AA talk takes away from our focus on the Raven.
Currently I believe that the Raven is honestly too cost effective to be "balanced," and other planes are less cost effective to be somewhat "toothless."
First let's look at just how cost-efficient the Raven is. This is a 300m unit that acts with raider speed and cannot be targeted by conventional units. Even if every piece of AA was cost effective vs Ravens, you'd still need to have AA at every location that it can target. Air players can easily scout with swifts (and no you can't really stop them from doing it either), so it's not hard to see targets of interest and any one of them can be bombed. Because of this you need to make AA on every front or anywhere you'd rather not be bombed, and you need to make enough AA to stop incoming bombers. Adding on to that a planes player may sent multiple bombers to overwhelm your AA. Now at this point a smart air player can fac-switch and completely nullify your AA until you can react to new ground forces. At that point you have to fight ground forces and cover all your valuable assets with AA; I hope you can see the building expense here.
The scenario above assumes that all AA is cost effective vs bombers in general, and I hope you can see why air is inherently powerful. Now let's take a look at what actually defeats a Raven cost effectively in the static AA section. Assuming that statics are more valuable than mobiles we'll check cost efficiency here to see if mobile AA even has a chance.
4x Defenders stop 1 Raven for a total cost of 320m, this is arguably the most cost-effective solution as the Raven doesn't get to drop a bomb.
2x Razor's cost 560 metal and do not stop Ravens very effectively. One Razor can sometimes work, but it's so rare I'm not considering this case.
1x Hacksaw costs 400 metal and can trade effectively against a Raven,
however, it's easily overwhelmed or baited.
I'm going to stop here for a moment because anything after that is getting to statics too large to reliably build in a 1v1 setting. Each of these solutions cannot cost effectively trade with small numbers of Ravens, and while they stack well into late game, at that point you're likely going to have to worry about a fac switch. Please take a note to remember that you'd need to cover all your valuable (expanding or otherwise) assets on the field. A large multiple of these defenses may be needed to stop even one Raven from cost efficiently bombing you with zero-attrition.
Furthermore, this assumes that you have all this AA built when the air player has just one raven, take an example where your opponent has 2 because you took time to scout.
Tl;dr planes are inherently powerful, we don't need one that can bomb into static AA cost effectively.
