Actually, Phoenix, 'tis the Commanders choice, whether he wants to comply...or not.
Of course, if he can not (or will not) and can get a word in edgewise (somethimes difficult) he absolutely should, no doubt about it.
It is the controllers job to provide the separation, plain and simple, anyway he can.
IF speed doesn't do it, then sending an aeroplane around from time to time is certainly within his/her perogative...as it should be.
You must understand that certain airlines have rather rigid standard procedures, and especially if a (for example) new First Officer is being trained, the line training Captain is going to darn well see to it that these SOP's are complied with.
If the price is going around from time to time, or holding a bit longer, so be it.
And speaking of going around, this may well only affect a few, who continually plan to uplift absolute minimum fuel at departure, thereby possibly embarassing themselves once they arrive in the London TMA.
For these, I can only say...its your own damn fault.
Tough beans.
120.4, don't lose your rag over this whole affair, just send the malcontents around from time to time, and ignore the complaints.
Hey, the young co-jocks need the flying time anyway.