A little canon violation and its fun to try to figure it out. A little more and you over look it.
Too much and you wonder if you can take the show seriously because it messes with your ability to suspend belief for a while.
If you ever watched a cartoon or show from the 60's, 70's or 80's it would be easy to understand why.
One example is the Klingons having smooth small foreheads in the 23rd century, then later have ridges. Its fun to imagine why.
Another is from Voyager--- the Borg being known and studied by Federation scientists decades before first contact--though the Federation never heard of the Borg before in TNG.
That one is hard to make sense of.