Because every time you try to have a serious conversation about it in the MOD, the Army suddenly leaks more than a rusty bucket and the Telegraph, Mail etc are running stories of outrage that we may no longer want the theoretical ability to dump several hundred guys a few hundred miles from friendly forces with limited support, and stretching our C130 fleet to the limit in the process.
Parachute capability is up there with the household division in terms of 'things we probably could do differently were it not for the Army being resistant to any form of change'...