Claremont likes his anti-heros and he seems to have a weakness for both Magneto and Dr Doom imo.
I would not quite say steal imo, the hero having a previous relationship with the villain is something not that rare in fiction and even there Claremont did a spin on the story, Xavier and Magneto donīt disagree on how they perceive each other they had a lot of respect for each other since day one and seemed to enjoy interacting with each other, they only had ONE, MAIN disagreement born from their own very different life experiences and that was the reason why they became enemies, as JDW once said, it must have been quite frustrating for Xavier and the X-men to have a potential ally that could do so much good for the X-men mission but that always went too far so they had to fight and stop him.
I see Reed and Victorīs relationship much more different: they got into a competitive relationship over who was the smartest from that one, that only got worse after Victorīs acciddent and Reed feeling some personal responsibility over it but they both had very different perspectives on the world problems and how to solve them even if they share some of the same personality flaws.
I also loved Victorīs time as Infamous Iron Man, now that heīs feeling nostalgic for a child it would be nice if he went to look for his child from that story and yes I see what Slott did to Victor pretty similar to how the 90īs were for Magneto and only because marvel canīt seem to be able to develop new villains interesting enough to get the readers attention. I completely sympatize with you here but I also think the new Dr Doom solo is quite good for him I just hope Darkhold has the same quality.