Like a lot of worthy people, he very likely p!ssed off the office-wallahs in Whitehall. Paddy Maine (SAS) was another; 4 DSOs but never a VC. Albert Jacka VC was another; he should have got a second VC but he was too critical of management. If you google him, you'll realise the MC he got at Poziers was even more impressive than his VC action at Gallipoli. C'est la vie.
As a paratrooper, in most armies you're called upon to achieve tasks that you wouldn't give a regular infantry unit.
And to do so with a smaller unit than you would choose in an ideal world. So, paratroopers are by nature, tougher, more resilient and more deadly. They set themselves apart from the rest of the Army and anyone who isn't a paratrooper, is a 'cr@p hat'. Paratroopers were a new concept in the British Army during WWII and regarded with a degree of ambivalence. Pine-Coffin may not have had to do anything, other than be a para officer, to be passed over by promotions boards. Pure speculation on my part. To understand how special the Parachute Regiment is, watch the recent Falklands documentary that focuses on Goose Green to Stanley. This was the first time that I'd heard exactly how many Argentines were dug in at Goose Green and when I heard the numbers I almost fell over laughing at how lucky the Paras were, not to have been wiped out.
As regards Paddy Maine. He seemed to have only two settings. Unexploded and exploding. Churchill enthusiastically backed irregular forces aka commandos, because he'd witnessed how successful the Boer irregulars were against the British a few decades earlier. While the SAS achieved results out of all proportion to their numbers, they were untouchable. But, come the German surrender, they were chopped post haste, by Generals who couldn't wait to wield the axe. Being an Ulsterman and unconventional, never won you friends in the British Army and still doesn't.