Trend in Portal 2 Mapping?
Me too, I think there is a huge space here for custom stories, especially in mods. The Portal 2 campaign brings us to the test chambers behind-the-scenes, but there is a lot more behind these scenes.
I'd much rather see a nuclear plant-like reactor with cooling water, glowing lights, pipes, Aperture Safety-Controlled Uranium Containers... 
That picture you showed totally reminds me of half life 1.
Aperture Science: We do our science asbestos we can!
I have tried several different "alternate themes". I once tried to create the mining facility that acquires the moon rocks. I thought about creating the main reactor. I even have tried to create levels that use mechanics from OTHER games. None of these things ever really got off the ground. The one thing that I have successfully was based on the shake flashlight. You can find it on here if you look under my username.
It basically uses the momentum principle of portals to create a sort of perpetual falling inductance generator that needs a cube to power it.
I did come up with a new idea today that might actually work. GLaDOS "pumps sunlight in from the surface" to create hard-light bridges, right? Well, what happens at night when the sun sets? Wouldn't the bridges fail to function any more?
they might. would explain why lightbridges arent used much near the wheatley boss, because it was night time when that happened.
another idea; what about the borealis? As huge a role as it plays in portal and hl2, i'm suprised nobody has tried making a map that takes place on-board.(well, i did, but that was when i was extremely new to portal 1 mapping...that was even before my mod h2f. XD) it could be pretty cool; considering it's position in a giant ice ravine. there could be caves that connect to holes in the ship's hull, and it's a huge ship. would make for some pretty interesting environments. what if the aperture scientists made tests inside of the glacial ice caves? the possibilities!!
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Sorry, what about this?
http://i.imgur.com/v4tn0Vl.jpg
please
please
another idea; what about the borealis? As huge a role as it plays in portal and hl2, i'm suprised nobody has tried making a map that takes place on-board.(well, i did, but that was when i was extremely new to portal 1 mapping...that was even before my mod h2f. XD) it could be pretty cool; considering it's position in a giant ice ravine. there could be caves that connect to holes in the ship's hull, and it's a huge ship. would make for some pretty interesting environments. what if the aperture scientists made tests inside of the glacial ice caves? the possibilities!!
I remember screenshots of a borealis level a long time ago. Which were really, really bad. I think they scared off people. Generally speaking the interior of the ship is either rather boring to look at (lots of tiny corridors that look really similar) or are very hard to get right (like engine rooms, control rooms) etc.
as for custom themes, well executed versions are awesome, not well-executed ones aren't. I think it needs time for people to get familiar with all the things involved in portal 2 mapping before they can start with custom themes. More custom themes will surface when more people are so familiar with portal 2 they feel like they can do it. And after 3 years that's happening more and more 
