My normal instinct would be to add in the missing glass in the display case, but with the way it extends past the supports at the top, it looks to me like it's supposed to be that way, more like a sneeze guard than a case. Normally with a dilemma like this, I'd try to figure out what's most logical, which requires answering the question "Why is there glass there at all?" (beyond smashing up real good). In the Star Trek future, dust and fingerprints don't seem to be an issue, so it wouldn't be to protect the models from environmental damage. It probably shouldn't be necessary as a "no touching" barrier, since the models wouldn't be super-fragile. I have the thought that it could be a transparent screen, and it might be able to activate and show some sort of infotainment program on the earlier Enterprises, but transparent screens were kind of rare in the TNG-era, and they wouldn't be necessary since holograms would make more sense for a rarely-used show-off feature that would only come up when visitors were killing time waiting for a meeting to start. Except it wouldn't be rarely used! I just checked the movie, and there are no screens in the FC Conference Lounge. So what if the sneeze guard is the screen, and it turns opaque when someone needs to show a visual aid, similar to the holographic viewscreen? And, like the holographic viewscreen, everyone decides they hate it after the shakedown, and it gets replaced with the big mainframe-looking thing and, I don't know, the bridge is moved forward four meters for some reason so the two rooms aren't directly connected anymore.