It has a big target on its back for a few reasons:
1) Money. Monsanto (Bayer) has lots of it and people - especially lawyers want it.
2) It is among the most widely used of any pesticide. There is an anti-pesticide crowd...they will do anything to get pesticides eliminated and they think targeting RoundUp will do that. The reality is that eliminating glyphosate is far more likely to increase overall insecticide use and likely lead to more toxic chemicals being used. There is now dicamba resistant soybeans. Dicamba volatilizes horribly causing more off target damage than glyphosate ever has.
3) There is a certain group that abhors Monsanto...almost to a comedic level. Best I can tell this has to do with GMOs....but Monsanto/RoundUp is evil incarnate to these people.
4) Money. It is ultimately about the money.
Nobody outside of a CA jury actually thinks glyphosate is a major player in cancer. even the WHO says it is a "possible" carcinogen...but they don't release the data they used to come to that conclusion. The US EPA did a review (with public input, and published the data they used) and again concluded it is not likely.