ATC workload
I think was on duty at the time, and if it's the incident I remember, I can probably give a bit of clarification.
The pilot in question informed us that he could accept an IFR approach, even though he did not have the appropriate plates, but as he'd only recently obtained the qualification he'd rather not. He would prefer to descend visually through a gap in the clouds he could see.
Fine, apart from the fact that that gap was over our holding fix, and directly on the climb-out for the runway in use at the time. There were several IFR departures, and numerous other bits of traffic and co-ordination, which as usual, all seemed to need doing simultaneously.
It was probably the fact that the pilot in question seemed completely oblivious to the fact that there were other aircraft around, affecting what he would like to do, and his persistant badgering as to when he could do it, which increased the workload, and led to the report being filed.
The other factors (poor planning, etc), only served to reinforce this.