Perhaps its an impact statement; and by that I mean it sounds good when discussed in a sound bite, but the reality is more than disappointing. A pithy gesture from a government, struggling to incentivise the electorate mid-term? Are they becoming worried that the military covenant is frayed beyond recognition? Perhaps. No matter what the motivation I agree that it is badly implemented as those who will benefit from it the most are the ones who work in London and would be willing to commute in 'rig'. The majority of HM Armed Forces don't work there, won't work there and certainly wouldn't willingly travel around there in uniform just for a free Zone 1 pass.
I bet the option for non-uniform travel was on the table but they looked at the projected cost and decided perhaps they had better stump up the cash for the Bomber Command Memorial instead. At least that was news-worthy and a triumph of common sense.