I think there's plenty of room for people to object to the "had to change licenses" framing. They chose to change licenses, same as they chose the original license.

That original license probably helped them with goodwill and to gain a community; when those benefits no longer exceeded the downsides of using that license, they changed licenses to one that suited them better.

Naturally, this change costs them some amount of goodwill, a portion of the very goodwill that they harvested by choosing an open-source license in the first place.

There is no bad guy. The OSS license meant that AWS was perfectly free to do as they did. If the companies who licensed their software as OSS didn't want that, then they shouldn't have used an OSS license.