Makes sense explained like that and from your own experience I can see why your assessment is as such.
In CQB we have noticed that for several guns the difference between the .12s and the .2s is as much as 80fps. 80fps may not seem like a lot but at the extreme ranges of CQB many have noticed that it is the difference between if a target gets his head back into cover before your BBs arrive or not.
An AEG example would be the TM G3 SAS or its clones, these have been used locally in CQB and as I have one of the sub-par clones I have been looking at performances of each brand and variant. The difference between a .2 and a .12 is often 50-70fps and at ranges of 30-40 feet that extra snap is much harder to 'Matrix' or dodge. Since the TM and its clones all fire in the 200-300fps region we found the difference between a low 200 and a high 200 seems to be key. With most people firing at least a 3 round burst the less accurate .12s hold their own in that area of the field (in the long range areas the .12s are completely useless).
A pistol example would be many of the Co2 pistols- here in BC the season is much warmer and there are plenty of Co2 pistols in use. With a nice .2 BB you can get a good 300fps which is plenty fast but with a .12 many of them get closer to 380-390 fps (I should add that our field has rules on fps which are lower than that for pistols with .2g BBs but that the owners also consider J energy so that the fast .12s are still 'safe' at CQB distances).
The tradeoff is that the .12s have less mass and so though they have plenty of snap the wind carries them... so often the shot is fast and useless. The .2s are of course preferred for all the reasons stated- more accurate, better quality and availability. Yet still some folks prefer that extra speed (they just fire 3 shots where perhaps only one would be needed with a more accurate weight).
I guess my contention is that though many or most people wont find that (good) .12s are of any use to them there is a CQB style of play that makes very good use of them (one of the guys uses a KWA M4, and his TF 11 with .12s and he has made very good use of the lighter BBs). In this case the fellow is looking to do some indoor shooting and at those ranges a .12 might very well be suitable (I vary my ammo between .2, .23 and .25 mostly but do have a springer UHC revolver that does much better with .12s) As such I would hate to dismiss any aspect of the sport- even those hated .12g BB lovers
I guess my thinking is that so long as it keeps players playing and they are happy I dont care what they use so long as they know all the pros and cons.