My take on Snake Eyes is that he has always had the ability to talk but chooses not to use it because he has had nothing worth saying for 25+ years. Even when he speaks he will deny it. I find it is a fun character trait to play with and almost always gets a laugh.
SE still has his bad-assery intact though, although I have no plans to use him to take out 5000 ninjas I do on occasion have him taking care of large groups of bad guys. The most recent, as of this writing, is a team up between him and Jason Vorhees. Not a fun day for the bad guys.