The existing public sector pensions contribute a few billion a year to the treasury, so the changes aren't motivated by short term need, let alone the recession etc. The teacher's pension scheme was recently evaluated by the government in depth and found to be sustainable, which again challenges the "need for change".
The Tories just want to attack public sector pay and benefits as they would rather it was all private sector. This would reduce collective bargaining power and make the ordinary man more shaft-able, including private sector employees who would not have that benchmark to compete with.
The pensions are a big disincentive for any private provider to offer currently public sector services. It's the single biggest obstacle to contracting out the whole NHS to private providers.
Since Gordon Brown started the process of dismantling British pension schemes in the late 90s, with the abolition of ACT, they've eroded the benefit incredibly quickly. The state retirement age rises relentlessly.
Some of this may be inevitable, but the government proposals are dishonest. The introduction of the average earnings, combined with an inflator of CPI are designed to systematically erode the value of pensions. It also provides future governments with a tempting fiddle factor to shaft existing employees.
So I for one am right behind them. We're far too compliant in this country compared to Europe, which I blame on a combination of the legacy of WWII and the Protestant work ethic that's driving us all to insanely hard work for relatively little reward.