True, but there are some good sources for back issues. I checked Paizo's site and The Hit Pointe, and at the moment both have all four issues in stock.
I've bought Dragons from both sites in the past, and been very happy with their service.
The maps in Dungeon are just blown-up enlargements of the one in the FRCS. Had they added more details (missing roads, sites, villages), it would've been interesting but in my opinion those were quite unnecessary unless you have a dedicated gaming table you want to plaster.