Have to agree whole heartedly with Airbus Unplugged on this on!
The company SOP for the £8 of fuel saving is flap 3 on a 321, I had to ammend that to flap full in a very heavy 321 the other day as we were following a very light 319 at 2.5 miles and our Vapp was 149 with a 15Kt head which was going to screw us behind a 319 at 117 kts Vapp.
I always try to warn director of an excessivly (sp?) low or high Vapp as I do realise the problems it can cause and the potential for go arounds. However, the idea of packing in the landing train at 2.5 miles per aircraft be they 737/757/319/320/321/MD80 or even the dear old Fokker 50 and demanding we all meet the 140 after 4 is a receipe for problems.
ATC are, I'm sure, well aware of the pitfalls and I firmly believe that early communictions on director helps the cause.
As Airbus Unplugged says we are human, we are aware of the problems and we DO try our best to juggle the various variables to achieve as close to what ATC want as possible.
T'aint always gonna happen.
W2P