As someone with drawers full of OS maps spanning the last 70-odd years, bookmarks to more mapping sites than I can shake a stick at, and a well-thumbed UK atlas in the pocket behind my drivers seat, I absolutely agree with the idea that people should learn how to read maps and use them more frequently for route planning.
However... I *also* own both a dedicated TomTom unit and the TT software for my WinMo phone.
Familiarising myself with the expected route and the basic layout of the roads along the route is something I find easier to achieve with a traditional map, and I generally aim to memorise enough of the route such that if I can't get right to the destination without further aid, I'll at least be close enough such that I could easily pull over, have a quick check of the A-Z/atlas, and be back on my way. So in theory at least, I should never need a sat-nav.
In practice though, if I'm travelling through unfamiliar areas where I don't know the traffic patterns and where the route I've planned turns out to involve the use of the most heavily congested roads in the area, being able to call up an alternative route that skips the jam ahead is quite handy. As is being able to reroute around accidents, roadworks, unexpected/unmapped changes in route accessibility (roads that used to be two-way being turned into one-ways, junctions being remodelled to stop you turning right etc.). Sure, *sometimes* I know the nearby road layouts well enough to be able to reroute without assistance, and *sometimes* the amount of rerouting required means it would only take a few seconds of studying the map to figure out a new route. But not always.
Sat navs and maps complement one another. Yes, it's a bit stupid to rely solely on a sat nav, but it's equally stupid to assume anyone who uses a satnav is doing so only because they don't know how to read a map.