Withoutwax, that is the point of the active traffic management system.
When the roads are dry, traffic reasonable/light, sunny weather, then there is no need to open the "hard shoulder", indeed, to do so would endanger anyone who breaks down & has traffic travelling at 70 mph(+!) bearing down on them.
The reason to open lane 4 (hard shoulder) is to facilitate extra traffic when demand requires, ie poor visibility, heavy traffic etc. This can only be achieved by limiting the speed so as to safeguard people in broken down vehicle that cannot manage to continue to one of the extra areas reserved for broken down vehicles (every 1/2 mile).
Many cameras are continuously overseeing the area & if a vehicle breaks down the opened hard shoulder is immediately closed & a VOSA vehicle dispatched to assist in the removal of said vehicle.
You will NEVER see the inside lane open without a speed reduction in place, which of course is monitered by speed cameras on many of the overhead gantries, which are adjusted to the indicated limit in force at the time.
The whole point of this system is to allow a greater number of vehicles through the area at a constant speed (possibly as low as 30 mph) at times of greatest needs, ie bad vis, rush hour traffic, it is not there to increase average speeds when conditions are good.