What I mean with MMA seperating the wheat from the chaff is that we've ended up with a very successful basic formula... Western boxing for hand techniques. A grappling system that takes whatever will work from BJJ, Catch as Can Wrestling, Folkstyle (high school and college freestyle), Grecko Roman, Judo, etc. And kicking techniques from Muay Thai.
This covers a huge amount of techniques and as you said an MMA practitioner has freedom to build a skill set that works with his own physical build, abilities, and mindset. Hell, if you're Chuck Liddell fuck the boxing and just go in there with some really good unorthodox karate stand up and a great take down defense built up through a lifetime of folkstyle wrestling. There is no wrong, there are only techniques that work or don't work and it's painfully obvious that most martial arts are packed to the gills with techniques that just don't work or are impractical.
BJJ has a LOT of techniques for submissions, but what you end up seeing over and over are the rear naked, the arm bar, and once in a while the kimura. BJJ looks down on leg submissions so you usually won't see a BJJ guy use one.
Leg submissions are a GREAT tool to have in your arsenal however, and that's why you'll see sambo and free style grapplers use them. Still, there are a lot of those too but what you'll see win a fight are the knee bar, heel hook, and Achillles tendon lock.
As Bruce Lee said, it's not the adding to, but the taking away. I think it's rather obvious that modern MMA is the true spirit of JKD, and I really feel sorry for those who believe that JKD is what Bruce taught to his students and that it would never have evolved beyond what he left behind.
I'm glad that you're training MMA. Krav Maga is a fucking lie.