When the usability of a the service (device, whatever) depends on, or is proportional to the number of other people using it, then adoption rate becomes very important not only for the success of the service, but it's usefulness too.

i.e: There can be a sewing kit that has a high learning curve, but would result in faster production / better products. While this may result in the the kit not being (economically) successful, it would still be just as useful to each individual who bought it, and learned to use it properly.