I get why a registrar would ask a domain
owner to provide a letter on an official company letter head when requesting DNS changes. However this is not the case. The registrar is asking for a letter from us. We are not the domain owner. We are not the ones requesting name server changes. We just happen to host the servers the customer wants to use.
To put it into perspective, its like saying that Godaddy should send an official company letter on a letter head to Hostgator when client A wants to host a website on Godaddy using a domain registered with Hostgator.
And yes Adam, we use cloudflare. We have had excellent service from their servers so far and see no sense to maintain our name servers when we can get a great service for free.