A lot of new investor/web users will go with Godaddy, these aren't your average domainer with dozens or hundreds of domains. All that high profile advertising spend works. Godaddy want you buying all the web/service bolt-on and when that remains affordable why not. Most businesses aren't going to be that picky over a few hundred dollars if it gives the stability, affordability and service add on that appeals. I doubt they'll even look elsewhere.
Domainers are probably (these days) a pain in the arse for Godaddy. I wonder just how much of this continued growth is down to additional services sold.