Tony Vargas
Legend
The initial lack of an OGL, and the restrictive/risky nature of publishing under the GSL probably had a lot to do with it. A lot more, in all likelihood.TBH I think this was THE main issue with 4e. WotC simply did not factor in, at least properly, the negative effects that a closed DDI would have on the wider D&D community. ... I think they miscalculated the extent to which 3PP would be locked out and just how much that would hurt the growth of a larger community around 4e.
DDI did arguably cannibalize book sales. The way they've priced it for 5e, this time around, shows they figured that out - the new CB will charge you by content. It still might eventually cannibalize book sales, but they'll still get the revenue, release-by-release.Notice how there's nothing like DDI for 5e. I mean, now, finally, after more than 4 years, they've released a product.
WotC was not being friendly to 3PPs at that time. The GSL was delayed, and toxic when it first came out. The whole thing was so effed up it provoked conspiracy theories (WotC trying to 'kill' 3pps by yanking the rug out from under them and forcing them to destroy GSL products after they've been printed). Compared to that, DDI being mostly vaporware seems minor.Its clear that Goodman and a few other 3PPs really wanted to be there for 4e, and they really tried hard.
It is too bad, because the underlying flavor of d20 used in 4e and D&D Gamma-World was in many ways much better-suited to other genres than the SRD version that's served for 3.x and 5e.