Don't think anyone here will disagree with that.
UK Police forces are getting squeezed for money at present though. Those who have not gone, will be less likely to throw money at "high profile" expenditure at present. By definition, those who have not gone already are going to be reluctant. Kent is really the most extreme case - other forces without Air Support tend to be tiny and rural.
Turn the argument around, Air Support needs police on the ground to make the arrests! Sometimes it seems there is no one there!
My take on this though is that publicly funded helicopters should be operated as joint emergency service helicopters. It reduces the area of operation for each hele, which makes it more effective. It also makes better use of under-utilised expensive resources.
The problem lies with government department empires. There is no incentive for Home Office aircraft to be used by Health Department and vice versa: quite the reverse. A real shame.