I think it's a good change. There's something that's hard to solo, which is fine, but then there are things which are impossible to solo by virtue of mechanics that demand multiple players. Razorgore the Untamed is a fantastic example of this. He's not even remotely difficult as he is, it's just that the multiplayer-reliant mechanic makes him pretty much unsoloable. Having to drag up someone to help kill Razorgore in a raid that's otherwise a total joke isn't fun.
I doubt that more bleeding-edge solo attempts will be affected by this change, except where they're absolutely impossible due to mechanics. Possibly like Valithria Dreamwalker for non-healers, for example.