Dragging clips into Vegas
 

I sometimes find it convenient to open a folder and drag clips directly onto the time line instead of using the Explorer tab in Vegas. Is there any reason that I shouldn't do that? I assume that dragging clips onto the time line accomplishes the same thing as selecting them in Explorer.

None that I can think of. There are many ways of accomplishing the same thing in Vegas, to allow everyone do what feels best. This is one of those things. I do it that way, too, by the way.

Vwgas Explorer direct to timeline
 

No problems at all. Just drag them to either your Project Media bin or the timeline. Works exactly the same as using the Explorer window in Vegas. What I would like to see in Vegas is to be able to right click in Project Media or a folder in Project Media and have an 'import media' selection.

That's an excellent idea and worthwhile recommending to Sony on their Product Suggestion page.
If enough of us do this, it might get added on.