It is if you haven't configured yourself for it. With high enough armor it just takes you down into the red. I have used it several dozen times on pretty much every Strike Mission Boss on the Tiger Playlist and only died once because I hit myself with a grenade just before I did it. Of course on higher raid level difficulties it isn't feasible, but you should be using Defender in those anyway.

I'm a level 30 Titan, even with my armor maxed out the melee hits from bosses are one shots unless you can get back fast enough, which isn't always easy because of how fast they their melee triggers

Guess you are unlucky then I rarely die. As I said if you are hitting raid level bosses with it then you probably deserve to die. Its not exactly something I suggest using on a Raid boss.