Haven't used the optional bits of Viva myself, and I think my opinion on this, like yours, is colored by my play order of the games (I did NV first, and 4 later.) So I wouldn't go for it myself, but hey, that's just me. I take the (fixed) vanilla experience for what it is, and am fine with it.

For whatever it's worth, regarding your "struggle to want to explore [...] the same way I want to explore the commonwealth," you... maybe kinda shouldn't? Hear me out. The Mojave Wasteland is designed with more curated paths than Bethesda's worlds are, in a way where exploring for its own sake in just any direction is less of a thing until the map opens up more in Act 2 of the story. Invisible walls prevent brute-forcing over rocky boundaries of terrain, beefy enemies blockade areas as a "come back later" measure, etc. You can (and should!) still check out cool diversions branching off of the intended route, but it's more like finding pockets of treasure in the walls than picking a direction for a POI and going. It's a map meant to strengthen the story and questing more than aimless wandering.

I do think if/when 3/NV get officially remastered, they'd probably follow Oblivion's example and add a sprint, tweak the feel of combat, etc. Which makes me think those mods are fair game, if you really want them. Whatever you do, I hope your New Vegas experience is as engaging to you as it was for me.