I don't know if we ever publicly hears about any specific rift, but a large number of folks like Magianello or Luke Gygax were in with the WotC D&D team for a spell fairly recently, and that fell off hard somewhere along the line. Don't know the exact tea, but it has been years since Luke Gygax...
I don't know what to expect exactly, but merely 3.x CC ain't it.
If they were smart, they would find a way to monetize he idler editions too, on Beyond or at least DMsGuild.
That could have been done by now. Thst it has taken this lot, and specifically what they were skipping around at this panel about the history and legacy of older editions well before anyone asked about CC...
It seems from the panels here at Gary Con that when Dan Ayoub did his goodwill tour with various D&D influencers and folks, when he met Luke Gygax it went pretty genuinely like this:
That assumes thst all they had planned is to just put out 3.x in the CC, when it really seems their plans were more ambitious than that...jjst not a to priority.
They spent a lot of time here talking about OD&D, AD&D, Basic, and even 4E.
They do release a number of diverse books every year. The mlre focused release schedule compared to earlier editions seems more likely to be part of the sauce of 5E success than a weird mystery.
It is pretty explicable as being low on the to do list. The 5E conversion document for materials from older editions, suchh as it was, took two years to release.
Having watched the full panel now, it is worth noting that the WotC team acknowledged that they have something to announce about older editions and the OGL/CC soon...
To add, there are some hints that this may have started as a DMsGuild product spearheaded by Gygax, that WotC got excited about when shown it and decided to throw their weight behind it?
And I have no doubt thst a Dark Sun product would have a lot of DM creation tools in the form of the DMG or the FR DM book : most people homebrew their adventures. People who want pre-written Adventures might have a taste for more generic, based on what we see get released.
The new Eberron book has a large amount of DM prep material. Thing is, is there actually a market for non-generic Modules...? The "I like something different from FR/GH" crowd and "I like rewritten modules" crowd might have little Venn overlap.