1st problem- only the HW1 models were released as open-source. There is an excellent HW1 mod out, just look through a few pages on the modding forums.
2nd problem- a new race mod is never 'simple'. It can be easy, but it is nevery 'simple'. A great deal goes into making a new race that is complete. A race mod is easier with a completely original style race (EX: the custom races in the 7 Deadly Sins mod, probably a couple of others). A race mod with a base on existing or established 'canon' (pardon the Warsie/Trekkie-style talk) is much harder to do accurately.
Then you run into the problem of the turrets- HW1/2 has 'em, Sins doesn't. Not orbital defense turrets mind you, but moving, animated turrets.
Sorry if it seems like I am just trying to put you down, I'm not.