This year on one trip to Europe I easily found a situation where only PIN (couldn't prove whether it was online or offline) would work, no cash option, because it was an unattended gas station in late evening with no one around in rural western Norway.

Now, I had the foresight to not actually need gas at that time, but if I had really needed gas at that time, no signature card nor cash would have helped (at least without waiting a possibly very long time on this empty road until I could flag someone down who could accept cash and use their card to let me gas up a little).

I thus classify not having a (perhaps offline?) PIN as something which could cause a big problem but the likelihood of running into that problem may not be big, depending on your exact situation.