Its because people don't understand why reworks happen or are needed to begin with, its not if a Frame isn't played as much or as seen as bad, mostly because these are purely subjective or preference based. Its for when a frame is struggling in the current environment of Warframe, or if they were designed to do something, and they do it poorly, or what they're doing doesn't necessarily align with what DE wanted from that frame. Yea some of the frames that got reworked previously were seen as bad or were underplayed, but reworking them didn't change that.
Oberon for an example is in a much better place than he was prior to his rework, yet he isn't seen anywhere outside of places where healing in needed, and the player and choose not to play Trinity. Speaking on trinity, because of her existence there are still players out there that think that Oberon is bad or irrelevant and is still in need of another rework. This can apply to pretty much any Warframe that's been rework recently, with a few exceptions like Sayrn, she was already widely seen and played already, reworking her did make her better, but other than nothing much