I've been saying for a while the Cybertech grenades are op. Everyone that runs RWZs regularly knows how cheesy they are - similarly to the bubble-break stun issue we're also seeing. It gives classes that don't normally have an aoe stun/stagger access to a free ability on a 3min CD. It breaks the rock/paper/scissors balance of PVP, and they are ridiculously abused in warzones (just like Adrenals). Only a matter of time before BW removes them from warzones... probably in 1.6.
This is a very good post that nicely sums up the argument for the OP.
While it is true that grenades can be used by anyone, can be acquired cheaply or crafted by an alt, giving every class a ground targetable long-range AoE mez disrupts balance to a significant degree.