Rob, I understand your point of view and do not disagree with it, but my perspective may be a bit different from yours. I appreciate the tools that the portal gives me to manage the hundreds of subnets that I handle and which allows me to make good use of the many volunteer coordinators who give generously of their time but do not have the time to manage their subnets the way you manage yours.
The portal has a DNS management function, but it is currently disabled because I have not figured out how to convert the existing DNS data to it and in that state it was confusing people. Being web based, I suspect you would have found it inconvenient to use as it would not have offered the unlimited flexibility of using an editor on a text file. - Brian