Well, it is possible to add fade to black on each and every track by way of adding a single ended transition, but that would be a hassle and it probably would not give you the result you were after. I suppose they could add an effect that you would add to the top layer, but that has never been requested by enough people I suppose.
I have a project that I import to almost every project I create.
That project has a sequence with Black video faded in, and one with black video faded out, and others with the same thing happening with a White matte. It also contains my logo and various other things I use in almost every project.
So, it is easy for me to apply a fade in or out by using the appropriately named sequence as a clip to accomplish that kind of task.