I think yes, but really tiny ones, in a color with a very low contrast with the background. Standard PowerPoint templates put huge page numbers, dates, and other graphical distractions on every page. It looks ugly, and having a visible counter running on your pages might make your audience wonder how many more numbers there are before the end.
Why still put them on (in a very small font)? It makes it easer to discuss comments/improvement suggestions on your slides, it is easy to run a meeting with printouts and related to that, it makes it easier to put your print deck together if you drop your pages on the floor.