There's been a lot of discussion on these forums about how long a game of NS should last.
If I'm correct then Flayra wanted to focus on quicker paced games but polls suggest that a lot of the community still want to play great epic games.
I suggest that the NS dev team accepts two types of ns map based on different criteria.
The existing criteria would serve the current maps which are 85% balanced and great for competitive play. A new set of criteria would be created for long haul maps. This might include requirements such as less resource towers, more entrenched positions etc . I'm sure we could easily come up with a list of criteria that would serve to prolong a game and make it seem more 'epic. You could also go one step further and have slightly different settings per map and specify the game style per map e.g. co, regular ns, epic ns.
I would certainly make a prototype map for this gameplay style if it would be considered (even though it might not meet current guidelines)