I agree, virtual space is sometimes very helpful. Examples:
* expanding into multiple cursors using ctrl-alt-(up|down); when the selection spans an empty line it thwarts many desirable column-oriented operations
* helpful in visually affirming the alignment of floating comments, etc.
Since Sublime already has the ability to trim whitespace from lines upon save, permitting virtual space should be nondestructive. This differs from how many editors handle it, where you end up with all sort of strange whitespace at the end of lines -- which in turn is confusing in non virtual space mode.
I would actually like to see a default of virtual space enabled and trim-whitespace-on-save option enabled. The combination gives pretty much all the benefits of virtual space without any of its downsides.