Two things - don't underestimate the political power of the Paras. Any attempt to take away their airborne training would be met with real fire. Secondly, there's a strong argument for retaining the ability to insert troops without direct control of a runway.
It won't be a brigade-sized drop, clearly, but the effect of a battalion of para-inserted troops plus AH-64 plus top cover could be just what is needed if HMG has to extract British/Eu civilians from a country where normal rule has broken down. Imagine the fuss at the wash-up if it was even rumoured that the lack of rapidly and flexibly-delivered forces had lost British civilian lives.