LJ has done it again...
Their latest updates - so far only affecting S1 based layouts (i.e. the standard ones), but threatened to be coming for S2 layouts soon - remove the subject lines from comments, as well as the Parent and Thread links, and Preview of a post is no longer possible. The new version of the user picture browser is a comparably minor issue to me (not to others), but it's annoying - you now get the images in non-alphabetical order, instead of the alphabetical list of their names. More info here - so far there are 134 pages of mostly complaints and demands for them to roll back this release. There is also this poll which you may want to fill in. If you haven't noticed any changes on your personal LJ or on the communities you own/hang out at, you will notice them when you go to the first link at the lj-releases community, which is in a S1 layout.
I seriously see no reason to remove the subject lines from comments - who would be bothered by them if they don't use them? However, many large communities like fan fic writing memes, RPGs etc. rely on them to make the community navigable at all - particularly communities that regularly reach the maximum number of comments in their entries! Why do LJ "fix" things that are not broken without consulting their users first, or at least giving them the option to opt out?! This is after all not a matter of taste, but of usability! And that one Russian developer who was working on this release got enough negative comments on his personal LJ that it should have raised some flags, frankly - but no, they go ahead and do it anyway! So if you have an opinion about this latest rollout, do go to the links above and voice it - in the hopes that they will at least listen if there is a large enough number of complaints!