Motif of Motives
The arbitrary local numerical value of this quantity depends on the arbitrary old definition of the metre from Napolean's time. After some international political wrangling, some French guys measured the meridian from Dunkerque to Barcelona in the years 1792 to 1798. If they had chosen a different geographical location the platinum metre bar would no doubt have come out slightly differently and maybe, with a little stretch of the imagination, we would not be plagued with awkward values for c today. As Einstein said in a lecture in 1921:
In order to complete the definition of time we may employ the principle of the constancy of the velocity of light in a vacuum.
With emphasis on the word may. The constancy of c was not to be taken as a fundamental consideration, but as a convenient means of defining clocks for observers in uniform motion. To assume that the constancy of c should suffice for quantum gravitational clocks is rather stupid. Fortunately people have considered alternatives. Louise Riofrio has some very pretty pictures and graphs which use a varying c to explain away the magical Dark Energy.