I agree. I might've been fine with the change if they removed breach and replaced it with pierce, but it's too much as it is. Personally, I don't think breach was really a problem. Lightsabers cut through all manner of improbable things in cannon, and they do it better than vibroweapons. Given that the system is attempting to emulate theme rather than achieve pure parity for the sake of balance I can't see why a weapon not even really meant for use in the current game needed a nerf.
Yeah..I hate to say it, but the Lightsaber, as it was, was a brutal, nasty piece of work. Also, it does not require much special skill to use its Breach ability…the nice, slow, melting your way through a bulkhead. However, I think the reason it got the nerf was that Breach was so nasty. Personally, I agree that it should have gotten a high pierce instead of Breach. Like maybe: Pierce 6. I think, though, part of the reason for not doing that was that there might be the idea that the best armour in the game, with superior quality, boosted by a Bounty Hunter should be the equivalent of made with Mandalorian Iron, or lined with Cortosis, or made with phrik metal…so that skill with the saber would matter.
Still…I think it should have gotten a Pierce rating if they were going to drop the Breach.
As for Vibro weapons having a higher viscious then a Lightsaber? I think that is because the lightsaber is, pretty much, a clean weapon, while vibroweapons have all sheer forces from the blade vibrating back and forth. I can see that boosting the critical chance if it manages to crit, while, when one can get a presumed Lightsaber Skill, the Lightsaber can, theoretically, get some heavy hits, especially if you manage to get a Triumph or two thrown in….