Honestly i fail to see the relevance of this thread.. There already is an option to have a spawnshield and i think the current default (OFF) is good for 'a basis in all game modes'.
If you want a improved shotgun take a look at the crylink or the hlac! Both are capable weapons in the right hands. Currently that shotgun is not too powerful which it needs to be as a starting weapon but it can still pack a punch closeup or with three primary shots even at a certain distance.
The whole arsenal of guns in Nexuiz is nicely balanced and all of them are quite usable and can deal lots of damage. If some people use the nexgun more often i guess its because they feel like they can hit better with it then with others. I mean what the hell, in SVN there are effective counter guns like the machinegun, the campingrifle and a lot of general useful guns like the crylink, mortar, electro, hlac..).
It seems most people that complain about the nexgun are ctf players.. well there are nexguns ON BOTH SIDES of the map, use YOURS too or one of the counter weapons in existance. In other games modes just try to control the nexgun so you enemy does not get it!