As for the FX, personally I think they are a cool addition to have. Yes the idea was to give a clue where the other team was being defrosted, *IF* you are paying attention. There are also actually two different sounds and colors, one for each team, so when you do hear it you will know if its friend or foe. However I can see the FX could be a problem if your team is down 15 to 1 or something like that. You could also use it for bait to get them all to rush a particular location and lay in wait for them. Or use it to lure them away. Might actually make for an interesting tactical weapon. A fake defrost with a little bit of weapon fire noise to distract the enemy.
1.46 does have directional audio for freezing/unfreezing. Carries to a distance of 2000 units. That said, sound distance is being adjusted.