is it just me, or is Disney trying to "overwrite" the more popular (or at least memorable) Legends stories?

It's not just you. The reason they're doing it is because if they use the old characters/settings/plots, they have to pay Lucas (and possibly others?) royalties, whereas if they use their own characters, they keep that money for themselves. This is likely why we keep seeing "the same thing but just different enough for copyright" over and over again, and why there's an increasing shift towards new vs. "legacy" characters.

(It's not that they'll stop using old characters entirely--especially the popular ones!--just that they have an economic incentive to focus on new characters, and that's a major influence on their storytelling choices.)

I think I've recc'ed this before, but Secrets of the Force: The Complete, Uncensored, Unauthorized Oral History of Star Wars by Edward Grossman has numerous details about the sale to Disney and the company dynamics, and everything I've seen thus far is consistent with this account.