and there was no reason that they couldn't have included that with plenty of expanded, non-moddable, distinctly identifying stuff coming later
I feel like that's exactly what they did, though. They released a generic, expandable, easily moddable system: the d20 system. People have had years to play with it. Some people (see: Pathfinder) are still playing with it.
Then when that was established, they came out with a distinctly branded, more interdependent and less generic game that's built on that system (yes, 4E is still a d20 game).
I'm glad that the restrictions mean that new developers can't just start cranking out new material immediately... the game's pretty intricate compared to previous editions (I don't consider 3E to be "intricate"... it had a bunch of unrelated subsystems, with more ones coming out as they had to sell more splatbooks) and you really have to get to know it pretty intimately before you can create things that will work well with it.
In the time since it launched, the dev team has been very forthcoming with commentary about their design choices and with tips for people who are creating custom content. If a 3rd party developer cares about making sure their content "works" with the game then they have now had more opportunities to learn how, and if they don't... well, the official content has now had enough of a head start that they're unlikely to damage the brand.
Re: D&D
I feel like that's exactly what they did, though. They released a generic, expandable, easily moddable system: the d20 system. People have had years to play with it. Some people (see: Pathfinder) are still playing with it.
Then when that was established, they came out with a distinctly branded, more interdependent and less generic game that's built on that system (yes, 4E is still a d20 game).
I'm glad that the restrictions mean that new developers can't just start cranking out new material immediately... the game's pretty intricate compared to previous editions (I don't consider 3E to be "intricate"... it had a bunch of unrelated subsystems, with more ones coming out as they had to sell more splatbooks) and you really have to get to know it pretty intimately before you can create things that will work well with it.
In the time since it launched, the dev team has been very forthcoming with commentary about their design choices and with tips for people who are creating custom content. If a 3rd party developer cares about making sure their content "works" with the game then they have now had more opportunities to learn how, and if they don't... well, the official content has now had enough of a head start that they're unlikely to damage the brand.