You say this so dismissively.
I'd count myself as one who doesn't think that just because this gets repeated often, it must be true.
The problem is that Shoaib is an injury prone fast bowler. He's not the first, and certainly won't be the last (I remember being frustrated with Gillespie's constant injuries, but I don't remember people taking so many stabs at his fortitude). Akhtar's biggest problem is his big mouth, which makes him a target for those that think he's too big for his britches (he sometimes is, even if he sometimes isn't), and who want to tear him down for being too soft, for pretending to be hurt, for not listening to Imran Khan, or having too long a runup, or whatever.
There's no guarantee, whatever Imran Khan may think, that Shoaib will be the same force with a shorter runup. The only time we've seen him attempt it was late in the test series, and to me, he looked terrible. Maybe he can persevere with this and improve, maybe he can't - it just isn't a given, as people seem to imply, that it will make him a better bowler, or more consistent, just because there are great bowlers out there who did it.
Personally I dislike how the issue becomes what Shoaib HAS to do, when he's still the best fast bowler Pakistan has, and he seems to get very little credit for the effort he puts in, especially considering his sterling solo efforts this last series.
I had thought that the comments in the Australian press by Ponting etc were just the usual psychological baiting. First he gets criticised for not shortening his runup, then, when it's shortened, the Aussies are "surprised" he wasn't trying harder, and steaming in to take their wickets. Not unusually, it's a no-win situation for Akhtar. Pakistan's biggest concern should be his bowling support, rather than constant attacks on Shoaib himself, IMO. Maybe leave that to the opposition.