I travel international 3-4 times per year for work and hardly ever get a SIM card. I use Wifi based services (iphone-to-iphone texting, What's App, and sometimes Skype to keep in touch with family). My iphone has also historically been locked and I wasn't motivated to buy another. I now have an unlocked iphone 7.
The main driver for getting a SIM for my upcoming Rick Steves tour is the maps, but a nice tip I recently saw on this forum is using "maps.me" and I've downloaded maps for the countries I'll be in and it seems to work pretty well. Any other travelers skip the SIM and not missed it? Any reason maps.me didn't work for you?