against good snipers, it was never helpful because they could just entrench in anticipation of your electrodart.
This. There was a use for the 30m stun though. More than one actually.
Sometimes you'd see a Guardian change his focus target to you and he'd of course start with his Saber throw. If you were fast, you could stun him before he could leap to you. Very useful. You can't do that any more.
Also, if you were tasked by your team to target and kill an enemy Scoundrel/Ops healer, you could eventually work him down below 30% health and then of course you'd need to stun him to finish him off. Being able to do that at 30m was huge. Now you can't do that and instead must bring your toon to <10m. Which is perilously close to the enemy's copious stun abilities. So killing an enemy stealth healer (the most common type of course), is much harder for Merc dps.
Which is the entire point of course. Every patch has exposed the devs desire to pare back Merc dps effectiveness. They honestly believe that Merc dps is the most OP class in the game.