I'm not a fan. The government are trying to justify it and point to the figures that indicate that safety has improved - in NET terms they are safer because the concrete dividers in the median have all but eliminated crossover incidents, but nearside collisions have rocketed up.
All sorts of other issues as well to consider. Should the government be encouraging or enabling more and more unfettered car use in the environmentally conscious times?
But even worse, they're merely a fudge. If you truly need a wider motorway, then there is no actual substitute for a wider motorway, in the same way dividing your spare room in two with a curtain is no substitute for moving to a house with an extra bedroom if that is what you really need. Successive governments are fans of the half arsed, the bodge, the shortcut done on the cheap - they never work, and remedial, measures further down the line mean it'll inevitably cost a lot more than if they had just done it properly to begin with. No, no, no, no, no!