Well, the subject is more than subject lines. It's alerting those among my friends who might not already know, that LiveJournal plans to institute some changes that will, among other things, eliminate the subject line from comments, and the ability to use a drop down menu to choose icons for comments.
The second is irritating in the extreme for those of us who have a large number of icons, and don't want to have to hit the browse button, then wait for them to load in order to make our choices.
However, of the two changes, the first is by far the most functionally irresponsible. Why? For me, in one word, auctions. There are other words, like "ficathons", "fandom stockings", and "fic-memes" but the first word is the most important. Without subject lines to order auction bids, auctions on LJ would be unmanageable.
And without auctions, the remarkable and inspiring ability of the LJ community to come together to respond to disasters like the Haiti earthquake, the Pakistan floods, the Gulf oil disaster or the Japanese earthquake and tsunami, would have been damn near negated.
But I'm sick, and my ability to type is at a premium. Please go over here to readwendymr's excellent post. It has the details of the changes and - most importantly - suggestions as to how to respond, and links on where to respond.
No matter what part of the LJ community you're involved in, chances are that these changes, and others wendymr mentions, might, or will, affect you. If you feel the same way, I urge you to take action.