I'd say the bridge looked very modular and reconfigurable from the get-go, with all those wall panels promising to reveal interesting functions, or sockets for such, if opened. The Helm and Ops stations also appear "loose" (just as in reality), as they are seen changing location between the pilot and the regular eps. The changes for ST:GEN thus don't surprise me at all.
What function they might serve, though... The back stations during the show were not used all that much, really. Perhaps the ship was prepared to take onboard a visiting party of researchers who would work directly under the watchful eyes of Picard?
I had thought something like this might be the case.
If we hypothesise further, the Astrometrics/Stellar Cartography room in GENS was considerably different to the one we saw in the television series, so maybe all of those areas were given an upgrade for some specific mission that we never got to hear about? The additional bridge stations might be linked to those upgrades.
Eh, I didn't care for the changes--the lighting or the set re-decoration.
It seemed a bit of change for the sake of change. We're doing a big movie now, so let's change the bridge because we're doing a big movie now. Especially nuts if they already knew that this bridge was gonna be trashed and tossed after this movie anyway.
Both in-universe and RL production, it still seems odd.
If they wanted to upgrade the bridge with elevated sections and a chair for Worf and a few side consoles, it would be within the series production budget to accommodate such things. But they never did.
Like I said, change for the sake of change.
Some of the humour in RedLetterMedia's video reviews might be a bit suspect, but he was
on the money when he commented pretty much this.
I used to be a fan of the GENS modifications (which I thought made the bridge look more 'busy', ergo making it cooler). But I've come aroung to the other way of thinking now: that some of the changes were unnecessary. Personally, I would still have lowered the lighting levels, but otherwise I'd have left the bridge 'as was'. The additional stations look kind of neat, but in some ways they stand out in a bad
way. They don't really fir the bridge that we've all come to know and love for seven seasons.