I think the SAK is at least partially defined by the corkscrew. And holding an eyeglass screwdriver is a very good use.
Dedicated corkscrews are probably going to be better, true, but what is your technique when using the SAK? If you screw the cork in and use a motion similar to closing the corkscrew, you can lever the cork out quite a ways and make it much easier to extract. It works much better than trying to just muscle it out.
It's still a mother-trucker to use that corkscrew on a wine bottle tho. It'll do in a pinch, but dedicated corkscrews are way easier.
Dedicated corkscrews are probably going to be better, true, but what is your technique when using the SAK? If you screw the cork in and use a motion similar to closing the corkscrew, you can lever the cork out quite a ways and make it much easier to extract. It works much better than trying to just muscle it out.