why not?
Asians go absolutely bat shit if you misuse their language, so why are we letting the whole damned internet misuse ours? Exclamation points have their own meaning. People who are educated, have ears trained to be sensitive to grammar, and are able to hear and feel the impact of punctuation, are offended by such abuse of our language. Exclamation points really can't be used as mere dividers. Using them in the middle of names is like screaming the name as if the character is being stabbed to death. I like these characters, and I don't want to see the English language bastardized in the service of stupidity.
You do know that you don't actually "hear" written words, right? If you're experiencing ear pain and auditory hallucinations while reading, then you should probably consult a neurologist or something of the like.
As someone with a MA in English and three linguistics courses--two of which were at the graduate level--under their belt, I can tell you that people who are "educated" are not actually bothered by this...pretentious grievance that you've invented.
Grammar is not necessarily static and rigid; even in the professional and academic settings, it's fluid and constantly evolving (which is why we currently have 16/17 editions of The Chicago Manual of Style). And then the internet has its own set of rules entirely...in that there ARE no rules, and most linguists will tell you that this is normal and generally accepted.
I hate to break it to you, but language is arbitrary. Especially the English language; there is no such thing as "bastardizing" it. For example, the earliest recorded citation of the phrase "bat shit" in the English language was in 1950 and was used to describe something contemptible--similar to how we use "bullshit" today. Then it was used again in 1964, but spelled "batshit" and with a completely different meaning: dull and uninteresting. The meaning of the term "batshit" as we know it today--"crazy"--was coined in the early 70s.
What is truly IMPORTANT in language is communicating thoughts and ideas to the target audience; if the audience is able to understand the speaker/writer's message, then language is successful! And I would venture to say that most people on the internet--particularly participants in fandoms and fanfiction--innately understand the Variation!Character trope, even if they cannot recite the where, how, or why of its origin. Perhaps it shouldn't be used in your thesis paper, but it is nonetheless a valid use of language.
I recommend getting over it.

WHY are they spelling these names with an exclamation point in the middle? Like Real!Ciel or Our!Ciel? Exclamation points have huge verbal impact, like a gunshot going off in the middle of their names. wtf? The entire internet is a sea of stupidity?