Not this again. How much of the time do you actually think 22xs are running at 125mph, anywhere in the country? Off the core WCML route, it's actually precious little. For example, it's all of 15 months since 222s were first able to reach 125 on any part of the MML.
A key feature of the design - and the 180s - is lots of power for rapid acceleration and climbing, which would come in very handy west of Salisbury, where the gradient profile looks like a rollercoaster.
And there is nothing stopping the speed limit on the route being raised where this is feasible if there is rolling stock that can exploit it, but doing so would be pretty pointless at the moment, wouldn't it?
Same as renewing track between Ely and Norwich can also be done, if needed, to allow use of 22xs at higher speeds.