If I understand your suggestion correctly, that would consume an extra 6 characters in the title, which is 8% of the 80-char limit. That would make it much harder to give each startup a place in the title, and I don't like the idea of leaving any of them out.
Personally, I click on the launch threads because they're part of the current batch: a clear indication that they're part of the current batch (rather than just a generic "launch HN" announcement) is much more valuable to me than the reference to the type of business. The "Launch HN" title is used by non-YC people, meaning these threads come across as non-YC threads than YC threads.
I think on balance you're probably right that excluding a startup from the title is a problem though -- so yeah, in hindsight, I think you made the right choice.
I changed it to say "Launch YC" instead of "Launch HN" this time round, for reasons related to what you're saying. Doesn't seem to have landed though :)
Another thought I had was "Meet S21". Better? It would free up a char! "Meet YC S21" is too long.
"YC S21" would be the shortest. That is, something like "YC S21: Foo, Bar, Baz" with a word or phrase for each startup. But I'm not sure if that would convey that it's a launch thread.
Another possibility: "YC Launch" instead of "Launch YC".
Our original idea was "Meet the Batch" but that's way too long.
Because it's a major part of the look-and-feel of the site and we don't change that without a good reason. Actually, we pretty much don't change that ever.
I would say the classic mistake is arbitrary redesign. Users hate change. Not inflicting random change on them is one of our secret weapons. Not saying we'd never do it, but there's a hierarchy of problem importance, and "need to have meaningful YC launch titles" is multiple levels below "don't inflict arbitrary change on users".
