I think when we're hobbyist, as most of us here are, there is no *need*, only *want*. Some people need full frame, or for that matter medium format (film or digital) for a look they want to get, or a resolution the client demands.
Some companies make stuff for the passion of it, I doubt Ilford makes black and white film in custom ULF sizes for the exorbitant profits and sky-high sales figures. 99% of companies make stuff for money though, and the only reason companies like Sony, Nikon and Canon are making full frame cameras to sell to hobbyists is to make us think we need them, and make crop factor cameras look old hat and rubbish.
That said, as hobbyists, the idea of using lenses for their intended focal length, the 'look' of larger formats, and the plain old pleasure of having something new and high tech may be all part of the hobby.
I'll predict that entire industry will phase out APS-C sensors in enthusiast cameras soon enough though, as making the most popular enthusiast format seem obsolete will be very profitable in new sales.