I use the front brake primarily and have only had rim wear issues on the front. Fortunately our area is pretty dry and we only get rain during the winter and early spring so that reduces the number of rides where grit is thrown onto the rims. My front rims last about 60 kmiles before the brake surface becomes too thin and I've never worn out a rear rim. So for me rim brakes are acceptable - especially since I get replacement Sun rims for about $20, reuse the old hub and spokes, and spend about an hour switching out the rim.
But the OP is seeing much more wear - which might well be due to different riding conditions. Commuting on rainy days on streets with lots of surface grit can wear the rim down quickly. So I'd agree with his plan to switch to a hub brake (either drum or disk) on the front and to use the rear brake only when really necessary (i.e. emergency stops and sometimes on slippery surfaces).