Marketecture.
It looks better to call yourself a NAP than to call yourself an IX. The naming of the "type" of exchange is by custom, and not law, AFAIK. Thus, the marketing droids take over.

Look at what they have done to "broadband"...

Maybe if we classed them by aggregate provisioned bandwidth, with a secondary classification that ranks number of peers at the point...

James H. Smith II  NNCDS NNCSE
Systems Engineer
The Presidio Corporation
I speak for myself, even when I shouldn't.