I think, from Hasbro's point of view, the issue is that no one is paying for the D&D OS.
They are in a situation where they had a tough year, and they are looking at how to turn things around. They go through their list of properties to see what they can focus on, and they've got this thing that has incredible brand recognition. But it's not making them very much money, especially compared to Magic, which is far more of a niche product but which has historically been a very strong earner that they strongly control.
So their financial people are looking at all the money that is being made in conjunction with D&D. They look at Kickstarters, they look at media (especially on the web, but you can bet they look hard at Stranger Things and Legend of Vox Machina). They look at Paizo. They look at tie in after tie in and work out that they are actually earning very little of the money that D&D contributes to. And then they inevitably start reassessing what the OGL has done for them.
And what the OGL has done for them is a lot less tangible. It has definitely been good for some small 3PP and companies like Paizo. It's been great for Matt Mercer. It has been fantastic for fans. But how, exactly, do you measure what it has brought to Hasbro/WotC? Nobody really knows how much it contributed to the success of 5e. So it's not like the Microsoft OS because Microsoft still got paid for every OS sold, whereas Hasbro doesn't currently receive a dime for a lot of products made under the OGL. What is happening now is that Hasbro is trying to make the OGL (or at least the updated OGL) like the Microsoft OS.