Why doesn't Sonar have this? It's so useful for adding bottom to your kick for certain genre.

I guess they could do a dedicated one but considering one could generate a low end sine using several of the included synths (I have layered kicks with a simple sine wav patch from z3ta+ and Rapture) or several freebie generators.  Not knocking the idea, just saying you may be able to get the results already.

Zeta2 does this. Initialize and choose sine.
 
In this video I show how to do it
https://www.youtube.com/watch?v=RKJxSQQRTkk