Whats with all the new skinned ships having the glowing bubble on the dorsal side or the sauser section? It started with the Venture Class, then Odyssey, now the Regent, and I 'm sure it will appear on the next cruiser they come out with or alternate skin. Its doesn't look advanced because the only canon style ship that it appeared on is the TOS Constitution Class. If its a glowing surface and it's not a light, engine, or deflecter, then it is made out of a translucent material, making it fragile. Why are we adding chandeleir parts for beauty, to ships thats supposed to be advanced and tough? In TOS days, its understandable things didn't have to make sense because in the 1960's that technology didn't exist and the science wasn't yet confirmed. Thats why you had ray guns the had an antena for gun barrel, computers with huge buttons and no screens.
Also, why are the bridge modules shrinking as the ships get larger and newer? The bridge of the Star Cruisers and Odyssey bridges look huge in the inside, but how you going to fit that great interior inside the small bubbles, you have as bridge modules? The size or the Regent's bridge module is like a pimple in comparison to the Galaxy bridge module. I'm sure the bridge interior is not the size of a closet. The Devs need to keep size of bridge modules and bridge interiors in consideration when they design new ships.
For the bubble, it could be fogged transparent aluminum of a fair thickness, providing just as much protection as a solid colored metal piece. As far as the bridge sizes, the sizes inside are more for convenience of getting around with 3rd person view controlled character with limited controls and having to deal with clipping of objects than an accurate representation of what the insides are like. Take a look on some of the engineering zones, there's what's obviously a ladder, but the distance between the rungs is about 7 feet and each wrung is several feet wide.
Seems to be an odd stylistic cycle, or perhaps every now and then some engineer finds a new use for this dome.
Possibly some kind of new sensor system that works best from such a location.
Perhaps because it's isolated from the other sensors so the new system and the older equipment don't interfere with each other.
At least until it can be integrated into the regular sensor pallettes on the next generation of ships.
Not sure there's any reasonable explanation anywhere.