Of all fights I've seen in my life, from highschool to my now 28 years of age, I have never seen a fight go to the ground. Sure, I've seen one of the people fall to the ground, and then perhaps followed by kicking or some such, but I have never seen the situations described here, where the fight turns into a ground/grappling game. Sure, it's not like I've seen hundreds of fights in my life, relatively few really, but still, never seen it go to the ground.
I remember reading a thread here somewhere, fairly ancient if I remember correctly, that took statistics from police reports done on it. From what I remember, the number was something like 10% of violent incidents went to the ground. Since I can't seem to find the thread again, though, take that number with a grain of salt.
About half of my real fights went to clinch, a form of grappling. The other half were knocked to the ground.
The statistics I offered came from various sources, but ALL stat's are irrevelant to an individual.
What I do know is that kicking, punching and striking -- atemi -- can be effective until you meet a strong foe...then grappling/seizing will happen: clinches, grabs, take downs, throws, and ground wrestling.
Hone your base, but be exposed to all other aspects of protection because that's FUN and may actually save life.
O-Sensei said atemi is 70% of aikido so I will maintain my karate base, flavored with occasional exposures to boxing, muay Thai kickboxing, & MMA.
MMA adds insights to all traditional arts. For the next few years I intend to concentrate on aikido to sincerely investigate.