Set Slide Numbering as the Default
Set slide numbering to be the default setting when beginning a new Power Point presentation. Everyone is using this program to present their information. In the educational sector, Power Point has become the text book of the this generation and the next. Will you please give our students page numbers for their text books?
in business context, people don't care for slide numbers. Audience will not ask "I have a question about slide 42", they say "I have a question about the pie chart you showed me" - so slide numbers are useless.
And your comparison regarding slide numbers in books: If you open a word document, you don't have page numbers by default, either. And people have learned to insert them there - why not in PowerPoint?
Alice Knotts commented
Teachers and other presenters are either forget to turn on page numbering, are too lazy to do it, or simply don't know how to turn the slide numbering setting from off to on. Making slide numbering the default setting would make a huge impact on the how the world is currently learning. (Basically, yes, Microsoft would be re-discovering for Power-Point the same discovery of whoever came up with page numbers for books.