That really sucks! Manysot was weak enough, and they made it weaker?
I'm with Rackhir - dazed and confused by this statement. Manyshot is incredibly powerful as it currently stands, allowing what is almost a full attack to occur within a standard action, and at a hit penalty that is so small to an archer as to be non-existant. Manyshot is more unbalanced when you add in something like haste.
While hasted, I have done a full attack (5 shots) followed by a manyshot for my partial action (4 more shots). The damage was so extreme that I stopped doing it because I thought it was just wrong.
And it's still fairly powerful. You are comparing it to what it was - instead compare it to your alternative.
You can fire a single arrow at your full bonus or
You can fire two arrows at -4 or
three at -6 or
four at -8
Yes it's one attack roll for the bunch, but that is not a big deal. If you're having a hard time hitting the monster, just fire one shot, or just fire two arrows and still do more damage than you would have before. If it's an easy target, open up. At 20th level, my BAB hovers around +40, so even at +32 it's not a bad option.
Combined with the haste change, this should bring things down to a reasonable level.