eh, I don't think people are over-estimating the A (unless they're planning on using it as a dedicated bomber)

speed is huge considering how squadron commands work, and currently the A-wing is the only squadron that can outpace a tie (or match up, since everything else is speed 3 or a B-wing) which means it's the only squadron that can "outrange" fighters and kill/engage before they start hitting your slow stuff. 4 health and counter do the rest.

Anti-squadron dice are only really going to come into play against Gladiator IIs or rebel mirrors. Any other star destroyer taking one die potshots at your As has nothing better to do, which is far preferable to what it could be doing to your capital ships

so yeah, As are what they normally are in star wars: anti-fighters (Except in x-wing minis where everything has to be anti-fighter). They intercept enemy squadrons to get them out of your hair, and the fact that they may do some ancillary damage to cap ships is just a slight bonus.

The other reb ships are slower and tankier and will figure into playstyles that can take advantage of them (Gallant Haven, anyone?). Otherwise, though, if you need something to check enemy squadrons specifically, I don't think you can do better than A-wings.

The reason why mobility is not huge, is because you want to be the reactive player, not the proactive when playing squadrons. Ordering 5 tie squadrons to kill Xwings and engage both Bwings and Xwings seems like a fine idea, but if you keep formation, the ties will be in range for your anti squadron batteries to obliterate them (have atleast 2 neb escorts if you are planning to play squadron heavy). If you add stuff like Gallant Haven there is absolutely no way they can engage your fighters or bombers in a way they would take advantadge of their mobility.

While you may disagree with Awing being a jack of all trades (as i do), it has been repeatly used to describe them, only awing swarms, why using anything else, etc... so i am just answering that point. Awings work as a cheap fast engager, you don't use them for their damage against squadrons or capital ships but as disposable tarpit. Since the game only has 6 turns, you can use some of them to tarpit your opponent's squadrons and try to complete objectives or harm/destroy their capitals.

Meanwhile, a Gallant Haven + Yavaris combo can wreck the Awings really fast with little damage achieved from them, allowing the more reactive player to get their bombers activated to deal with the capital ships.