The quick and dirty solution/rollback to the boss changes would be (in my personal opinion) is simply to lower their damage potential and leave the HP increase. This would provide a more equitable curve of difficulty from the minons to bosses.
If you think about it, even though they have more Hitpoints, this alone can increase their damage potential over time, allowing them to stay alive longer to attempt more hits.
My biggest problem with this isn't the soloing aspect. Ok, so now we gotta call teammates just to finish garden-variety missions that we used to solo... I guess I can adapt to that easily. It's the one-shotting potential and lack of fun involved when people quit groups or the game entirely because of changes that are very anti-player (in my personal opinion).
As some have stated before:
The level difficulty slider for missions would have provided the challenge people wanted.
The boss bump for average (Non-named AV wannabes, not full fledged Boss mobs who SHOULD be taken by groups, not solo) street type bosses was totally unnecessary. The damage increase and hp increase coupled with a mission difficulty slider only caters to the powergaming "I made my build exactly how it should be to kill with maximum effectiveness vs endurance cost and speed" A.D.D. Ritalin-popping players, not people who actually want to make that flawed concept hero, experience the content, have some fun with friends and *gasp* role-play.
If you want suicide missions, put in some contacts for that.
It's so sad that I've said "No, I'm not playing WoW or EQ2 with you guys, I'd rather play CoH" to some people I've spent years playing with, only to start to see the same trend that has hit every other MMORPG on the market (like EQ).
Next we'll have flagging, alternate planes of existence that you can't get to without completing 50 badges, 6 AV at once fights where you have to have 200 people to finish them....
The ONLY thing I liked about EQ that would be interesting in this game is Faction. That would introduce another dimension to the game: Sure, I'm friendly with the mob now for helping them by clearing Tsoo from their docks, but boy those Tsoo sure hate me for it more.
It's really funny, other than the boss change, I think the patch was ok for the most part.