As an aside, it's good they can laugh at themselves with the klingon theoris:
The Under-Resourced Creator Theory
This theory states that the universe is a creation of one or more beings, and that our universe exists solely for their entertainment. Being almost but not quite all-powerful, the Creator at one time envisioned Klingons as they exist today, but at that time was unable, with the limited resources at hand, to fully realize the original vision for them.
However, as time moved forward and the universe grew, the Creator was provided with resources vastly superior to the ones originally available, and thus Klingons were recreated in the original vision. Because every being in this galaxy is controlled by the Creator, few beings ever questioned the discrepancy and those that did were met with evasive answers, all at the behest of the Creator. Being a very busy Creator, there were always more pressing issues at hand than explaining the discrepancy, and thus the issue has remained a mystery to this day.
While someday the truth about this odd discrepancy in Klingon appearance may be known, it's entirely possible that the truth has been lost over the course of history
lol!
'Wish I could Help you....Wish I could tell you,
That I am real, I'm not something you invented,
That I'm not everything you want me to be.'
'And I am...Ageless. And I am....Invincible.'