It might make a number of people rage since their may have passed up on +11/+12 AAW as a secondary stat on some of their carefully rolled sailors. Will not change their gameplay but the ability to have a crew that can machine gun a sq of planes overhead would be a missed opportunity.
Lvl 120 pilots will still be AAW immune so possibly no effect, that is until immunity is turned off or at least nerfed.
Most USN ships still currently hold the highest AAW of their tier such as sodak and baltimore, which still works however not once enemy planes hit immunity.
US do lack +2 in some areas but they make it up later during other classings, for example, USN gets an additional +1 during spec forces classing over KM (next rival in fighters).
US also gets a +1 potential in landing and airlift over all other nations which makes their marines strictly better while of course other things still must be taken into consideration when choosing APA such as engineers and AA. Just an example of how national +2 means nothing where ship abilities and component abilities are factored in.