Tbh, I wish someone would make a mod for TTW to try and flesh out the FO3 companions to be on a similar level to NV companions. It's definitely possible, especially now with A.I. voice being a thing. I'd do it myself if I wasn't retarded and actually had talent in that sort've thing.
There IS a mod that is trying to overhaul all Fallout 3 dialogue to be more in-line with New Vegas but I haven't tried it yet. Not sure if it changes the companions at all.
Like for instance, Charon. I like Charon, he seems like a possibly interesting companion at a glance. You, like me were probably curious about why he's so devoted to his contract or whatever (All we know is that he was apparently brainwashed to listen to whoever holds his contract but it's never elaborated on.) only to be completely disappointed by his utter lack of dialogue and thus personality. This is a problem with a lot of the FO3 companions but I felt Charon was a pretty decent example of missed potential. I was genuinely disappointed to find you can't investigate his story all that much or probe him for any personal information because the little we know has potential to be interesting if done right but yet there's just nothing.
You don't need complex companions with a novel of a story to have them be fun. Companions in F1 were just random dudes, there was more going on to them in F2 but they were still mostly hired guns, aside from a few interactions they had with the overworld. Tactics literally had nothing going on with your squadmates aside from a few sentences of bio they have, but at least you can directly control all of them, and we come to Fallout 3 which mostly just goes back to your companions being...just dudes.
I very much prefer it this way, I'm not looking for a best fwend to tag along with me out on the wastes nor do I want someone's emotional baggage or judgement. I love FNV but I can only stand Boone, Cass and friends for so long when all I want is a hired gun. That's why I like Lily, EDE and Raul so much, they don't bore me with their life stories(Raul kinda does but his quest breaks most of the time).
Jericho, Cross and friends are all badasses without a need for a personal quest or doing errands for them, they're just glad to be there. That's honestly what I want, companions in FNV and F4 were all very fan-fic character like. London and Outer Worlds has the same problem for me, there is only one companion that I can stand in both of these games that is just a random dude and they're both robots(Pendragon and SAM respectively). Most of my modded in companions for TTW and F4 are also mostly just dudes, I can't stand the likes of Willow or Niner. I can play around with all these companions, sure, but most playthrus I just want no-strings minimalist followers with me.
Besides, their writing would be shit, it's Bethesda we're talking about. It's for the best we know very little about these companions. Hell, they don't even follow their own internal logic, why the fuck won't Charon go into the irradiation chamber that won't harm him if he's pretty much a brainwashed slave that has to do whatever you say? Because you need to pay for a DLC to do so, obviously. Nah, I will take Jericho with me instead, who just wants a piece of the action instead.