So, registration doesn't have to be onerous. Reporting income/profit is a pain, I agree, but may be a requirement from WotC's perspective. I am willing to allow it if it is specific to OneD&D, because we are not likely to get everything we want, and we have to give somewhere.
I think we have to dispense with the notion that current WotC is actually looking for that kind of 3pp support from this. The v1.1 terms were too hostile for that to begin with. I expect that at best, the OGL to them is for amateurs, and real 3pp support, if any, will be handled by other, more specifically negotiated license agreements.