The big selling point of the first Kindle was the idea that you could access the store to download stuff anywhere. WiFi wasn’t ubiquitous like it is now (and even now, it isn’t as ubiquitous as I think we all would have hoped), which made having a free 2G connection really nice, especially when outdoors in areas that the E Ink display really shined.
As much to the point, Amazon was also very much aiming for the use case of the business traveler who wanted to buy a book before hopping on the plane in an airport that probably didn't have WiFi and almost certainly didn't have free WiFi.
I won't say 2007 was the stone ages. But a lot of things we mostly just take for granted today didn't exist or were relatively nascent.
It did open up some very interesting homebrew applications too!
Also the early models with WiFi had the absolute worst radios and constantly tripped over themselves. When I worked for Centurylink in/around 2011 one of the most common issues with wifi was Kindle devices. Thankfully most customers could figure that if their 3-5 other devices were connected and working, the issue was their Kindle, and not the CPE.
But if you actually needed a working network connection in the press room, you plugged an Ethernet cable into your laptop.
We were surprised that it even had enough signal to figure out the GPS cords.
Even back then cell coverage was not as good as it is now. So many times it was 'go stand at the end of your driveway and try'.
Like my dad's house in Maine today :-)
In the early years of the iPhone in the US, there was--including on this site I imagine--much wailing and gnashing of teeth over AT&T's coverage.
edit: What I find interesting is that the things had location tracking built in and no one blinked an eye.