I have mixed feelings about the custom footprint service -- I've worked with ~900-pin BGA SoC-type parts, and paying $30 to do that would be a no brainer, but paying the same for a 8-pin LDO would be a tougher sell -- maybe scale prices with part complexity?
The tougher sell to me is trust / verification of the InstaPart models before the community can vote them up or down. For most teams that I've been on, the most time-consuming part isn't really the pinout generation, but rather the checking of large parts (often 2 engineers checking pin-by-pin to ensure that footprint matches data sheet). I'd be much more comfortable using it if you outlined how pinouts are verified before sending them out to the customers.
I hope this works out! Making footprints is a huge PITA, and I'd love to be rid of it.