I'm completely ignorant about D&D and the OGL so I'm not going to comment on it too much but from what it seems WotC wanted to move away from what is at the moment an extremely generous system that has given birth to it's main competitor (Pathfinder) and I couldn't fault them for wanting to wrangle control back and make money from people basing their stuff on the D&D system, its kinda scummy but there is no such thing as a free ride.
TL;DR the Open Game License was written to let anyone create expanded content that fits inside the DnD ruleset. This was generally a great thing for DnD, as it didn't replace core rulebooks that you still needed to buy, and meant that players had no shortage of well made content to play - People could actually make money creating classes, adventures, races, regions, errata and such for DnD, so they took it seriously and made some really good shit. This ultimately spawned Pathfinder - But only after
Last time they tried to fuck with the license. The thing about the license is that it was intended to be written to be perpetual, non revocable. Everyone involved in writing it has said as much. But they didn't use "Non-Revocable" in the document, they used other terminology and now Wizards is trying to use that to snake their way out of it, using a new license that takes advantage of the old terms to 'De-Authorize' the old license.
The problems with the new License are many, mainly that you end up giving Wizards all the rights to your content (They totally promise to not abuse it, but they also promised to never do what they're doing now, so take that with a pound of salt) and that they can collect royalties on all your sales and gatekeep anything in it, letting them decide arbitrarily if anything is allowed.
On the face of it, a license asking for royalties and putting some approval process in place isn't the worst thing, the problem is retroactively forcing that license on everyone, after you grew to massive pop culture popularity off the back of their work, just as much as they grew themselves in it. These people already know how to create interesting and engaging adventures that people want to partake in, which is why they're popular - rather than making more of their own, they're just deciding that you owe them some of that pie now.
The problem with this, which is rapidly manifesting, is that people aren't particularly attached to DnD - Which is why there is already a movement from the Pathfinder publisher, already joined by many of the major content publishers, to just cut Wizards and DnD out entirely, and set up a new open common ruleset and license to carry forward. Wizards can screech as much as they want, but game rules cannot be copywritten - just the specific, non-generic terms used to describe them.
They may have just inadvertently killed the golden goose with their greed, and its delicious to watch.
