Even really neat mods like Vikingr hardly get any players anymore.
the reason:there are more players with some crappy cracks,than players with original bought games 
so if vikingr had SP,it would be full of ppl
btw its a nice looking mod as ive seen so far 
good luck and hopefully you will finish it sometime
I submit another reason that you overlooked. Some of us have computers that are really shitty, so we can't run the game well enough to be able to do much in MP other then be a meat shield, which personally I DON'T FIND FUN. Not to mention that playing the game with the track pad on a laptop can be.... interesting.
im one of them

( my computer is old and has i think 526 RAm ,wich is enough to play singleplayer(with lag) but you won´t have fun in multi)
btw frisian i wish you very best and cant wait for the first release to try it a bit(as much as i can witht his computer) any chance we get a alpha out in few months???(or beta) I reall woudl like to see what this mod looks like?
im lzy so i dont want to watch all the pages of this mod, but is there a pic of the map??? if there isnt could you upload it? anyway as i said before good luck frisian