The problem is what about stuff like resolution lists, these need to be detected based on the players specs and screen, and some people have multiple screens which can cause a bunch of resolutions to be added to the array. The thing is generating this list in run time in a scroll menu would be an extrem pain compared to a popup list and these resolutions cant be split up theyt do all need to be in the same pop up list.
I really dont get the design problem argument. Its the same difference weither its a "popup list" with a "scrollbar" included VS a "scroll menu". The main difference being the popup list is a lot easier to generate its array list during runtime, where this is a bit more complicated and tedious with a scroll menu.
If other people have already added this themselves then it shouldnt be too difficult to do either, the problem with using their solutions is that you would need to re-inlcude those changes with each update of NGUI and if the internals change those custom fixes are useless then and need to be overhauled as well.