It's likely the devs saw the number of people attempting it, and decided that they wanted more people to be able to clear it than the percent that are currently able. I want all the fights to be super difficult as much as the next guy, but 8man was clearly tuned much harder than the rest of the instance, implying they intended it to be easier than it was.
I think the answer there is to tune the other bosses to a similar challenge level rather than nerf to get things lined up.
On wanting more people to be able to clear content - story mode was made for those who just want to see the content and mechanics and don't really want the maximum challenge. Hard mode is for those who like a challenge, at least on release. And Nightmare is for a select audience, those who want a true, nearly impossible challenge.
I'm of the understanding that a large amount of the former SWTOR player base left due to the lack of challenging raid content so I think nerfing is also a negative business decision.