The reasons to buy WotC is the same to be not sold. Today a "serie B" franchise from TTRPG can be very valuable thanks the right videogame adaptation, for example Cyberpunk 2020+Cyberpunk 2077. In only one day CD Market Red has made more money than R.Talsorian in a decada, hasn't it, or am I wrong?
Hasbro is not going to sell WotC if they are too busy with the future projects of action-live productions, for cinema and streaming series. Maybe Hasbro isn't totally happy with the TTRPGs and collectable cards, but the things are different if we talk about the potential incomes thanks the videogames based in WotC's IPs.
Let's imagine Hasbro talks with Epic Games for a future event with the name "Omega World" for Fortnite, abount the "island" being invaded, or visited, by the people from the TTRPG Gamma World (robots, mutants, antropomorphics animals..)... now Hasbro may be making money with the action figures based in this hypotetical Fortnite event, and not even a Gamma World book is necessary to be published. And in the next year there is a new serie on Netflix based in Gamma World, with cute "furries" (antropomorphic animals). Sorry, I mean if a "forgotten old glory" as the RPG Gamma World could become a potential cash-cow in the future and then they shouldn't reject the IPs. Hero-Quest, the dungeon-crawler board game was line for almost two decades, and today there is a second opportunity. If this project works... why not to try it with other old titles?
GW buying WotC? I would rather to suggest Hasbro(, or Disney), buying GW but today W40K is a franchise very "grimmdark", maybe too much and politically incorrect today. (I know there are kid-friendly books set in Age of Sigmar and W40K). I guess if GW is bought by a "bigger fish" maybe this asked a retcon of the IPs. (I know Age of Sigmar wargame with d20 dices sounds horrible. Why not d30?)