They are movies, they're just movies that are released direct to video. There is nothing in the definition of the word "movie" that excludes any particular medium of release. And they are officially called DC Universe Animated Original Movies.
What they are not is kids' movies. The DC Universe Movies are all rated PG-13, targeted at teens and adults.
Ok, so call them DTV Movies. The point is not the movie title, but that they are DTV instead of theatrical. Bruce Timm has said the 70 min runtime is because of budget issues. It's a simple fact that you don't make as much money from a DTV as you do from a theatrical release. Superman Doomsday was the highest grossing of the line and it grossed $9.5m. Superman returns grossed nearly 10 times that in the first weekend alone.