What type of work were jointers like that used for? I would expect any board you're using that is 30" wide is also at least 1.5" thick and several feet long. Trying to man handle boards that big on a jointer isn't very practical. Extra long would be far more useful than extra wide.
Casket factories used a lot of 30 and 36" machines.
I am going to make some of those lazy edge slab tables all the yuppies are spending crazy money on.