The problem isn't specifically Mt.Gox, it's the fact they like just about every other FIAT<->Bitcoin business, were wholly unprepared for the onslaught in demand. I cannot help but notice that Bitstamp (an often vaunted alternative) is as I write this, also offline.

Bitcoin as a technology seems pretty robust and fairly scalable but it is the supporting businesses that provide migration to and from traditional currency networks into Bitcoin and its derivatives that are the weakest link. There is no denying alot of this has to do with greed, FIAT<->Bitcoin businesses see huge profits if they realise the significant potential volume that has landed on their doorsteps, the only problem is their infrastructure (much like the recent upward swing in Bitcoin pricing) cannot sustain indefinite growth. Something has to give, and that something is more often than not the software underpinning these businesses. If a few of these businesses managed their numbers rather than operating an open door policy, it would be a win win for everyone. On the one hand some potential customers will be unhappy, but they at least don't lose any money and can always apply again. Likewise, the business can then scale its infrastructure gradually ensuring its existing customer base retains access to a functioning market... which is kind-of the whole point of this exercise.