They do not have to. Any one that does this and knows they will be interfacing with other products makes an API that will allow the communication. Hero lab already does and I would say it is harder as they are working with another company that is out of their control.
As for compliance, I assume yes. They have their own internal compliance and the other datasets they offer most likely have their own from anotherr company.
I notice you leave out all the 3.5 edition builders that were available.
Not addressing you specifically rjdafoe, but using a generic "you" to address those that think data modeling and api design is a trivial matter...
Do you know how to make an API?
Do you know how to design an API?
Do you know how to reverse engineer an API?
Do you know how to design a robust dataset?
Do you know how to model 4e as a dataset in xml?
Do you know how to model 4e as a dataset in sql?
Are you familiar with the following terms: SOAP, xsd, xpath, xsl, RESTful, varchar, DOM, wpf, liveconnect, xmlbean, uuid, xsl:fo?
Those of us that can answer yes to all that and more can truly appreciate what goes into someone else's piece of software, tell good and bad design choices, and instinctively gauge the general challenge of modifying something.
3.x/PF is significantly easier to model than 4e. SW SAGA edition is easier to model than 4e (another pet project of mine). Gurps is easier to model than 4e. 4e is a down right PITA to model, specifically bc it's exception based. There are a bunch of corner cases that are simple to express on paper as a rule or in your head when your playing, but are actually very complex when you have to break it down for computers.