In case anyone wonders where that poll was -- it's here:
To be clear, I'm just the developer for web/Welcome/Boutique related stuff, I don't actually develop MATE itself or touch other pieces of code for Ubuntu MATE.
I'll be here to defend the corner to ensure Traditional sticks to its values. It's more so that one of the objectives of Ubuntu MATE is:
Recreate the halcyon days of Ubuntu for users who prefer a traditional desktop metaphor.
This change would've resulted in "Menu, Places, System" which sounds like a Frankenstein... "Applications, Places, System" with simple drop-down menus is a very nice characteristic of MATE. 
I agree with @stevecook172001 that I too personally don't mind the default changing when it's for the better, but I suppose there has been no announcement as there hasn't been an Alpha release yet. 18.04 is still in development and it looks like it was an experimental change.
Development wise, it has been reverted for technical reasons I believe, especially if you consider users will be upgrading from 16.04 -- the experience should be as smooth as possible.
I too would not expect to see a "Traditional" layout that presented Brisk... that would be a lie. If it was called something like "Traditional: Supercharged" and set as the default, I'd be OK with that.