While it sounds good in theory, and adding judges might reduce the number of plea bargains a bit, I don't think it is a good idea. There are trade offs that make this idea not worth it.
Plea bargains don't just happen because there are too few judges, they happen because there are too many criminals. Even if we doubled the current number of judges there would be too many cases to try. Plea bargains also happen because some accused criminals might not be convicted, so some jail time is better than taking a chance on none.
But if we have less plea bargains, we have people in prison for longer. We would not only need more judges, but more prisons and guards. This costs a lot of money in a time when state budgets are being cut, not added to.