My two cents:
As mentioned before; there are many "older" cachers who use a GPSr rather than a smartphone for GCing.
When traveling internationally using Data on your smartphone can also be very expensive; in my travels to Events I rely on WiFi connections at the Hotel for Data. I would log the Lab Caches from my laptop in the evening. Having the GPX also allows for loading them easily on my Car GPSr.
How will offline finding of Lab Caches be addressed?