Is there any particular reason to think HTML would be high on the list of things they thought about when they decided this? It's not like the world wide web had taken over everything yet…
I don't know the exact considerations at the time – I wasn't there, and at "only" 38 I'm too young to have lived through it. But the argument holds for many different formats and protocols, I just used HTML as it's common today and I could easily find content for it.
For example plain text emails still have considerable ASCII data in the headers, no matter which language you use to send them, and depending on the length of your email UTF-8 may be smaller than UTF-16. I just checked a very simple email in my inbox, and it has 165 lines of headers for 21 lines of actual email body text (plain email, no MIME). Even after removing the more modern headers (DKIM, X-Spam-, etc.) we're still left with 35 lines, or 1,886 bytes. The actual email text is 765 bytes, in basic English. If the email text was in CJK it would still be slightly over 1K smaller* in UTF-8 (4,181 bytes vs. 5,302).
Longer emails would be smaller in UTF-16. I don't know what the average works out to, but ~21 lines seems about average for an email, give or take.
For example plain text emails still have considerable ASCII data in the headers, no matter which language you use to send them, and depending on the length of your email UTF-8 may be smaller than UTF-16. I just checked a very simple email in my inbox, and it has 165 lines of headers for 21 lines of actual email body text (plain email, no MIME). Even after removing the more modern headers (DKIM, X-Spam-, etc.) we're still left with 35 lines, or 1,886 bytes. The actual email text is 765 bytes, in basic English. If the email text was in CJK it would still be slightly over 1K smaller* in UTF-8 (4,181 bytes vs. 5,302).
Longer emails would be smaller in UTF-16. I don't know what the average works out to, but ~21 lines seems about average for an email, give or take.