I think that having something more like the originals playing every time we start up the game will hit that nostalgia.
I get no hit of nostalgia from BG3 whatsoever, so it makes little sense for just the main theme to do so. Perhaps, deeper into the game, once actual familiar characters start popping up a nice audio cue would be welcome?
I'd say it's the opposite. BG3 gives no BG vibes at all, so something should be done about it. There are "big things" that could be changed (party size, day/night cycle etc.), but there are also smaller things and tricks that can be used to evoke some of that BG feeling. Music is very powerful in this regard and could help a lot. And not just the main theme; all of it should be given a lift. Mind you, I'm not advocating for completely scrapping all of BG3 music; just tweaking it. As the mockup in th link I provided proves, even relatively small changes can make a huge difference. Familiar auditory cues could also be used. Again - not copy/paste, just reminiscent and in the same style.
