Let me add my 2¢: allowing case differentiation in tags is not just about aesthetics. It's about readability (coming from a book designer). Granted: it's not a Mount Everest among the issues because tags are rather short so most people won't even be able to notice the difference, but readability problem is there. The thing is that when we read, we don't read words letter-by-letter, we read the whole words or even clusters of words at once. It's because in all actuality we remember shapes of the whole words, much like Japanese remember their kanji (the difference is that in our case, if we don't recognize the whole “shape” we have a fall-back mechanism in form of known single characters).
Somebody mentioned acronyms like “RFC” feeling weird. It's not just “feeling weird”. In fact it's common for us to look for a specific shape formed in this case by upper-case letters. Let's take a list:
- Linux
- Windows
- SIP
- html
- JSON
- bat
- rfc
- xml
- Text
- RFC
- CSS
- txt
- json
- Hiragana
- Kanji
- Latin
Which “rfc” is easier to identify and locate? Which “stands out” more? The one that does is the one we're accustomed to link with the concept of that acronym in our mind and that one is simply faster.
IF YOU NEED MORE PROOF, THAT WE ARE READING MOSTLY BY IDENTIFYING COMPLETE SHAPES OF THE WHOLE WORDS, THEN TRY TO READ THIS :}. COMFY? I BET NOT! :} SLOWER, ISN'T IT? AND THAT'S ONLY A COUPLE OF WORDS. IMAGINE IT'S LONGER AND PUT IN AN UNBECOMING BLOCK. READABLE? CERTAINLY! BUT READING IT IS NOT A PLEASURE AT ALL :}.
That's it :}
Oh! And @dpoulton: “Furthermore, I consider that Carthage must be destroyed” ;}