While I agree that the intention behind the alternate spellings is a poor one, I find nothing wrong with using a different spelling, in and of itself. As anon posted above, almost all names in English are variations (both spelling and pronunciation) from the name in another language.
Would you described "Jesus" as a "moronically corrupted" variant of "Yehoshua"?
And yet, there is an objective standard.
You can't go making up your own spellings, like "Jesys" in the example you gave. In English, the name has already been imported and converted. It's spelled J-E-S-U-S.
When the answer to "why do you spell it that way" is "because EVERYONE ELSE spells it..." you know you're being a moron.
Kevin is the acceptable spelling in English for that name. Period.
Kehvyn
Kevynn
etc.
are OBJECTIVELY stupid attempts to be "unique".
Some people even (attempt to) violate the laws of English grammar as they pick the spelling AND pronunciation of a given child's name. That's really outrageous.
For example, one might name his child "Kevin" and insist that it's "keh-VEEEN".
Uh, no. Kevin, in English, is prounounced "KEH vinn".
And you didn't even touch on another issue -- making up your own names by changing the first letter.
Megan/Meagan is a pretty name, so let's call her
Began
Degan
Kegan
etc.
That's also just...stupid.
And those last-name-first-names are the most ridiculous of all: hunter, colton, etc.
I'm still waiting to encounter a girl named McKenzie McKenzie, or a boy named Jackson Jackson. Or a girl named Peyton Peyton.