I agree entirely its a real shame that more Arb businesses when they do have disposable capital (yes I know when would that be???) don't see the sense in investing in such tools.
If we left it to the "market place" (in Oz at least, since this is where I live and work) there would be no call for modern Arboriculture at all.....just top and lop mate she'll green up and if it don't well then just plant another.........
If we truely believe we have an understanding of tree biology that is not common knowledge, that we can offer positive long term solutions to a great many tree related concerns then that is what we should be presenting to the great unwashed.
We are not all working in the same areas I know that some of us focus on the coal face..saw in hand, 30-40m up a declining leaning Euc...I really understand that, I do....you know from time to time (increasingly rarely) I'm up there myself!
However working in the area of plant health care does affect the way you percieve the problems and the potential solutions...the air knife can be an important tool in that particular field of Arboriculture...and yes I wish they were available to hire!