As Kyle Kanos said in his answer, we just know *it is there*. We calculated it theoretically, and coupled with experimental evidence, we just accept that the speed of light is $c=3x 10^8 \frac {m}{s}$. 

I want to attack the root of your question. You see, we always expect everything to be as we like it. We want to have control over all around us, even nature. In Christian theology, the earth is at the center of the universe. Our inherent conception is that we occupy a central, priveleged position in everything we do, from relationships to businesses to our understanding of the universe. The reality is that we are anything but priveleged. Science has repeatedly shattered this misconception of ours, but we still hang on to the ego. I suggest you watch Carl Sagan's famous speech [*The Pale Blue Dot*](https://www.youtube.com/watch?v=XH7ZRF6zNoc) which puts accross this message so powerfully. 

In such a case, I think it is extremely unfair to expect the speed of light have a value that appeals to us, other than $c$, the universal speed limit. In your case, the question is not about why the speed of light has that particular value, but why we think it is not supposed to be so.