Topo maps are often useful in remote areas and don't often go obsolete (barring volcano's and asteroids) In populated areas the topo map is not so useful since buildings and chain-link fences don't show up and will often be a barrier. Road maps go obsolete quite quickly and therefore aren't much use unless you have a recent one. A silk map of a populated area that was printed in 1943 will not be very useful. You can get tyvek maps from the USGS for most of the remote areas of the US. These are not as multi-functional as a silk map but much more durable and just as lightweight.

Another problem in general with a map in the PSK is that the PSK or other kit carried for survival in unexpected situations, is that unexpected situations happen in unexpected places - you only carry maps for the places you expect to be. OTOH, it is not a bad idea to get a map for any area you are visiting or traveling through and carry it with you. If you drop from the sky in a jet-liner during a trans-continental flight and happen to live the likelyhood that you have the correct map in the overhead bin is very unlikely. In this situation, after praying your thanks to whatever god you believe in for the fact that you are alive you might find the compass much more useful as well as the general rules of walking out. - follow water down hill, signal for help don't stray far from the crash site - it will be most noticable from the air etc....