I don't think GA in 1.09 was a bug, there was a deliberate change made in the file missiles.txt: The column Pierce was changed from 0 to 1. In every other patch, this column is set to 0.
They/Blizzard probably just underestimated how strong GA would be with high Pierce %.
Imo they should've kept the feature, while for example changing Pierce so that every successful pierce lowers the chance of the next one.
It was definitely overpowered, but I've always felt that it only made sense that those skills worked together somehow.
Multiple Shot also worked differently pre-1.10, where every arrow applied special stats like Freezes Target, Crushing Blow, CtC, etc.
Would've been fun imo if they had nerfed that feature rather than kill it off entirely. For example they could've nerfed the % of the stats based on how many arrows MS fired, or something.
And Cow runs!
