I think its ironic that, effectively, WotC gave the fans the keys to produce whatever content they felt they weren't but we wanted. And with this newfound freedom, we IMMEDIATELY fell into the same products that glutted the d20 market in 2001; PC options, new monsters, and low-level adventures.
That's because you need to take
direction into account. As in showing the direction of the edition.
A fanmade psionic system is far less valuable to me than an official one for several reasons:
1) I WANT WotC to show us what their direction for psionics
2) official means much more usage, much more discussion, much higher confidence of quality and balance
Only as a distant third comes
3) I would probably not even find the fan made system on DMs Guild, unless it somehow creates so much buzz I can read about it here on ENWorld. (In which case it probably is so high quality that WotC should hire the author and make it official, leading back to 1 & 2).
It all boils down to WotC getting to eat the cake but still have it too.
The DMsG deflects the criticism that the system is closed while not meaningfully exposing WotC to either having to take market risks or any great competition. Note how the one thing we actually could do ourselves that would provide actual competition is support for other (official) campaign settings is not allowed.
They don't have to support psionics because we COULD create it ourselves. Yeah right.
DmsG is a win for WotC, but much less so for us consumers.
I would much rather the true nature of DMsG would be commonly known, so less people call it "giving us the keys" when we pay WotC to drive the bus for us.
"Giving us the keys" is much like a cab driver selling it as a huge win that you can now actually drive yourself to the airport...
It would be another thing entirely if WotC didn't use the existence of the DMsG to delay (or even outright not plan for) actual system support, and if they actually let us do what the community would do much better and faster: providing comprehensive officially supported community-driven 5E-era updated material for Athas, Cerilia, Eberron, and so on...