I don't see how hiding large chunks of code behind a drop-down is making it "easier to navigate in Visual Studio." If anything it is now much harder.

Plus you're now burying how long your class is and the individual methods within. So a class or method that would otherwise be inappropriately long now looks a reasonable length.

If you feel like the code is so long that it needs regions, then refactor the code, don't hide the mess under the bed.