I have to agree. In A2 the audio samples were far from perfect mostly, but at least the distance filtering was implemented quite good (explosion's, chopper's sounds etc.) But modern hardware could allow more features, even few years ago EAX could demonstrate interesting features as reverberation and echoes. To bad EAX technology is not supported many years.
I understand that BI is not a very big developement studio, but in my opinion such effects as reverb can be added to A3 quite easily. Say. There could be few zones (triggered areas) or objects (such as buildings) in Arma 3, those may have an attribute, which return a value to a sound engine, what kind of area it is - closed or opened environment. The rest will do the filters and sound FX. I believe in Bc2, BF3 and BF4 works same principle, with an addition of bigger variety of sound samples.

only as a reference:

fast forward to 7:00

https://www.youtube.com/watch?v=xcQ1IMUfa18

Yep, strange monotonic chopper sound, no matter if it's hovering, flying by fast or slow.