Probably best idea would be to increase that Nano reisist on root and a select bunch of other nanos to 150-200.
When doing so each professions nanos would have to be looked at for balance. For example some professions would find rooting easier than others in proportion to their other abilities.
Also note what occurs for players occurs for Mobs. If the average player is going to resist roots 50% of the time, then so should Mobs.
another idea is to give Doctors a Purge line (a fiixed one at that) to cast on people to try to remove hostil nanos, or alternative make Purge a line of Nano Resist buffs (Alpha +100, Beta +200, Gamma +300, Delta +450, Epsilon +600)