The TOS Connie bridge is different. It even changes the other decks. It's very retro. There's even clickies that do things like open the blast windows. There are even patients on the sickbay beds. There are still dupe officers on the bridge though - what's up with that?
Technically, we are in the TOS timeline, but we don't play in the TOS era
The Constitution bridge pack was a step forward for interior design, and I imagine that that'll continue with the Defiant interior for the next feature series. While it would be nice to see the Devs alter the interiors that we already have, I'm not holding my breath.