Considering that both the Conservatives and Lib Dems were trumpeting this before the elections only to drop it afterwards smacks of either deceit or stupidity; take your pick.
Trumpeting? It might have been touted as an element of policy after questioning, but "support for open standards" is never going to be a vote-winner in an election.
There is a large number of UK geeks who genuinely believed Tories and (especially) LibDems would have reduced the influence of Microsoft on public procurement once elected. I know because I've been surprised by this over and over (I live in the North of England, where being a Tory is, er, very unpopular by default, and with reason). For them, this issue was indeed a vote-winner, so this u-turn will hurt, especially among LibDems... but then again, hardly surprising by now.