I see the traffic / deconfliction service as it is provided at the moment as the lesser of two evils - the other one being more class D airspace. And I say that with class D airspace as it is operated in the UK, where clearance is less than assured.
Here is my example: Southend now has some CAT that wants deconfliction service. Our general handling / practice area is over St Mary's Marsh, and gets in the way if they have to provide 5 miles separation to an approach from the west, especially if we do climbing/descending and stalling exercises at around 3,000ft.
I always call for a traffic service, and Southend are VERY accommodating - I do not remember a single service refusal. On occasion, they ask me to work to the west side of the marsh, or remain a bit south, or remain below 2,000ft for 10 minutes. I am always happy to oblige, and it sure beats "basic service only due controller workload" from Farnborough.
I do not see this as overcontrolling - Southend certainly is asking politely - but as a give and take.
If that particular bit of airspace became Class D as during the Olympics, we would lose this training area, and I am certain that a clearance into Class D to do some stalling would not be something I could reliably plan to obtain...