Once, I had unlimited data. Then I wanted a new Moto X phone, so that was the end of my Verizon unlimited data plan.
That's the exact reason I've stuck with my old T-Mobile plan and just transferred between non-contract phones. 90% of the time, I'll be somewhere that has 3G, and 9% of the time I'll have at least 2G.
Having signal's nice, but it's even nicer if one can afford to use it ;)