I'm positive at this point that it was an intentional change.
OPs have quote/reply disabled because retards quote the whole thing just to add their two cents. That's nothing new. But it appears that the quote/reply is also disabled on "long" posts, for some definition of "long," presumably for the same reason.
Null has said that the highlight to quote is still supposed to work, however, it does not. The javascript that does the highlight to quote specifically looks for the "Reply" option, which doesn't exist, so it invalidates the selection. And even if it didn't invalidate the selection, when it creates the tooltip menu with the quote/reply options it actually just clones the quote/reply options from the post footer (which don't exist)... so the tooltip menu would just be empty.
The fact that the "highlight to quote" feature is also bugged is pretty annoying, since it makes it effectively impossible to reply without hacking the BBcode to make a quote that points to the right post.
What could be done is to hide the quote/reply options in the post footer for long posts (still have them in the code, but add a class that hides them). That way speds can't shit up the thread by quoting the whole post just to add two words at the bottom. But highlight to quote will work properly then, because the options can be cloned into the tooltip where they will show up.