I personally would prefer few to no characters were essential. I also would like to be ALLOWED to fail a quest if I want to (and/or refuse it and have it NOT show up in my quest list/move to finished/failed quests) (I HATED it in Skyrim when a gajillion quests got thrown into my journal that I didn't want and had no way of removing them; I remember I got the stupid lighthouse quest and tried to force fail it by killing the two Argonians who started it, but no, the jerks were marked essential, and even when I consoled their essential-ness away, it still wouldn't fail/remove the quest. SO ANNOYING.).
Obsidian proved it could be done right and well with New Vegas. Sometimes yes, your actions would prevent you from getting quests but it also almost always opened up storylines the way YOU wanted to play them, and I seldom felt railroaded. The many ways you could deal with Benny was but one example. If I wanted to kill him early and earn permanent hostility from the Chairmen I could. Awesome. I was fine with losing out on the star-search quest as a result. And the main quest was scripted well enough to adapt to that.
And indeed, I also want non-essential companions. I loved that Charon died protecting me from a Behemoth in Fallout 3, and I let his honorable and exciting heroic death stand. In Fallout 4, as I painstakingly tried to disable every single trap in Jamaica Plain and Deacon at the very end just decides to walk through the laser trip wires... you can BET if he hadn't been essential I would have let his sorry ass get turret-fired to death and have enjoyed that fact. (And indeed, it's annoying the real reason they made companions essential is because their AI makes them too stupid to live otherwise. Setting them to essential is the easy way out.) (And yes, if the companions turn hostile, their essentialness should shut off.)
BUT...
I also get that Bethesda is damned if they do and damned if they don't. Even if they do like they did in Morrowind, where they put up big obvious flags that say, "IF YOU DO THIS, THE STORY BREAKS," some total idiot who needs his hand held while he plays would complain AFTER getting that warning about how it's so unfair that he did this thing the game warned him not to do and then he broke his playthrough. For every person who's desperate to have real choices, consequences, and agency, there's two people who complain when they are forced to face the obvious results of their actions and complain nonstop about it. Bethesda has chosen to cater to the lowest common denominator--and honestly, given some of the feedback thrown their way, I can't really blame them. Shame it makes my playthroughs a little less fun, but I still do have fun, so I'll deal.