I'm living fine with a 3GB data plan (yes 3, not 30). It's only problematic if using tethering otherwise I have hard time understanding how people can consume more data just by browsing the web. Too much adult movies maybe?
Sitting there streaming video content is a nonstarter just from a battery life point of view alone; I wouldn't do it even on Wi-Fi.
Speaking of which, 1.5Gb is enough that I don't bother looking for Wi-Fi hotspots.
The mobile plan is such that if it goes over the cap, it will just stop, rather than incurring extra charges. So until it stops, why would you mess with Wi-Fi.