I find it completely useless myself, I have not seen a traditional can for at least 5 years. IMO it is just there as a filler tool that is cheap to make.
Here, the can options are basically 50/50, in terms of pop-top or traditional.
So far the consensus seems to be a combination of tradition and function, although I get the impression more for tradition. I NEVER use a can opener on an MT or SAK at home and if hiking and camping I don't want to lug around cans, "every ounce counts". At home in our kitchen we have a drawer right next to the pantry that has the can opener and other assorted kitchen tools in it. It's easier and quicker for me to grab a nice safety cut can opener out of that drawer and use it. I just don't know what tool could be used to replace the can opener though. I agree with the statements about not needing a dedicated bottle opener too. But at least the SAK bottle opener tip makes a nice flat head screwdriver and the tool itself is good for prying. And of course let us not forget the handy wire stripper on the bottle opener. But as for needing it to open a bottle, it's almost a luxury. I'm sure like most if not all of you, I can open a bottle with a lighter, table edge, etc.