I find it useful because search results still don't return the name of the author. Searching by user isn't exactly the same, because I might not have a specific user in mind, but still prefer to read an answer by someone I know gives good answers over the 52 answers by anon monk.

For what it's worth, I consider adding my name a work-around and would much rather have that extra bit of search information returned and leave off my name.

As for original topic v. new topic, I like to have both pieces of information. My ideal solution, of course, would be to have search return 'in reply to' and 'in thread' (and possibly 'nesting depth') so that the title would only need to convey the topic of the message, not additional historic information. (These could be super-search checkboxes or user settings to keep results simple when desired.)