All these things directly help increase presence. No more MGs, Luchs, etc. covering areas of the map? Now it's easy to get brit inf into cover for that stat bonus, probably on a fuel cutoff or something else that's critical.
Yes, in 1v1. However, 2v2 is also a valid and almost equal skill-requiring game mode. Short of rushing T2 (oh look no map presence), there's no way to get a pak out on time.
It increases your field presence AFTER the AEC hits, if and only if those things were giving you trouble in the first place. The question that was presented basically why make the AEC if it reduces your capping power.
You make the AEC in order to counter something that you are having trouble with. It isn't a unit that should always be built (like an M5 Quad or T70 for example).
Up until the AEC hits, you're going to be severely crippled in capping power and map control. Even after it hits you still need to purchase more squads to catch up on capping power.
Blindly rushing the AEC is asking to lose in a 1v1. If they don't have anything you need the AEC to counter... then what's the point? You're just going to run it into a PaK or Rak, spend all day repairing it and sweeping for it to what... bleed some Grens or Volks? A sniper or mortar pit can do that better while being considerably cheaper AND not delaying your Cromwell.
It is finally a good unit that fills a valid (and much needed) role in the UKF arsenal, and now everyone is flipping out? It is far from overpowered in a 1v1, and nowhere near the level of other things like Calliopes, M1919s, Quads, Ost snipers, IS2s... What would UKF do without it? They were already the weakest 1v1 faction before the AEC buff, and they're still the weakest Allied faction - and perhaps the weakest 1v1 faction still.
If the timing is really THAT much of an issue in team games, make the research take longer to finish.