I don't see it as defending GoDaddy at all, quite the opposite. I would be more reassured if it was an unexpected massive DDoS which they weren't prepared for but one which they might prepare for in the future.
The way it's described now is a weakness in their infrastructure of which I wonder if it's possible to prevent this from happening again.
"The way it's described now is a weakness in their infrastructure"
Godaddy has plenty to lose by f-ing up. And to my knowledge (as a somewhat small competitor; I'm just pointing that out so my thoughts are taken in context) they have a fairly robust system (anecdotal) for the amount of data they manage. My issues with godaddy (as a competitor) were always on the sell side, the issues of constantly selling you things you don't need etc. Technically I really didn't have any issues with them.