Well, i rarely play all maps included in a game, since the quality, balancing, theme etc. varies a lot.
As long as those 8 maps are well designed, they will be enough for me. It also depends on the game modes, still not sure if we can play survivor or conquest on every map.
I don't plan to buy the DLC, but might do that anyway, if i get to see the maps first. I think releasing 4 maps at day one (they are included in the hunter edition anyway, so they were always ready to release and didn't require any additional work), which is 50% of the stock maps, is kind of a rip-off. If they would release additional maps in a few months as an DLC/expansion, i wouldn't mind it at all and would actually appreciate that. I don't think that DLC are generally a bad idea.