My father taught me kenpo off and on over the course of my childhood. One of the things that sticks in my mind that he always told me, is that whatever happens don't go to the ground. I'm 5'3" and back then my senior year of highschool I weighed about a buck 18. Right about 16 or so was when the first UFC's started coming out, and my buddies were thrilled with the Gracies. Little guy, taking on these huge guys fighting them on the ground. Problem is some of those fights were very unrealistic for real world combat, in my opinion. Fights happen fast, without warning, bang! Your fighting for your life or a loved ones. You don't have 45 minutes to be messing with this guy you have to finish it and do it quickly! A fight starts going longer than 2 minutes and things start working against you.
Now is this to say that you shouldn't learn at least some ground fighting? Well, you should to be honest. The fact of the matter is I knew alot of good wrestlers in highschool. For some reason it seems to me that grappling arts have a tendency to be more effective in the beginning, and you don't have to always practice it once you learn it. Once it's on the ground you kind of have time to do some things. Time to think, standing your reaction time has to be a little bit faster. Like blindingly.
And who is to say that you don't have to fight one of these highschool state champs one day? If he was good, he might try to take to the ground if your stomping his face in with strikes. Lot's of people have learned lots of things, and sometimes it's that fat drunk guy at the end of your local 'Famous Sam's' who's just looking for trouble that night, and he might be a damned good wrestler.
As far as taking stuff from this art and that art, well even in JKD it's recommended that you have a firm foundation in something else. Remember Danny Inosanto was a Kenpoist when he started. This is something some you mixed martial arts guys seem to be missing. You could know a thousand techniques, from a thousand different arts, but which one are you good at? This is an important question. My belief is really you need to learn one, all the way through, to really understand what you can do with it.
Kenpo will change. I don't care if you are a traditionalist or not, you aren't going to do it exactly the way you were taught. Look at Frank Soto, and Ed Parker's son. They are changing the way they do kenpo. Kenpo for a long time was and in many ways still is a black or white art. It is a kill or be killed art. Now you watch Frank on You tube and see what he's doing and it's kind of getting more into the realm of Aikido style controlling techniques. So it's going to change, and there is alot of in-fighting with the various kenpo orginizations, personally I think that will ultimately kill the art if anything does. Plus you know you've got the Tracy's teaching there version, and guys Like Larry Tatum, it's natural and really doesn't need a discussion. At some point someone is going to add BJJ to Kenpo, just as it is with every art. Your going to add what you feel works. And it will be within the framework of the style that you prefer. So it's going to happen, and really the bottom line is what do you want your Kenpo you be, and have, and be about. Every student should take his art and make it his own. So that may mean that you add or take away, or whatever, and if you decide that you want to teach your kenpo then that's what you'll do. Then you'll have a whole new branch of kenpo for people to learn, and soon nobody will no what to expect from a kenpo practitioner. Hmmm....could be very interesting 200 years from now. Wish I'd be around to see it.