I've posted elsewhere on this matter. But seeing as this seems to be the main thread, I'd like to add my voice to the mix.
Regardless of whether the disabling of Topics page is for a necessary fix or improvement...
A. This should and could have been managed better. There are means and ways for coders to test changes before implementing changes live.
B. If it wasn't possible to test before going live, communicating with the WP users beforehand would have helped. I find it worrisome that, aside from one very vague post from a staff member that's buried in a thread that's since been locked, there has been no further information regarding this issue. No timeline, no official update, no nothing.
C. Not all blogs are online dairies; some of them are genuine attempts at building a business. The topics change is hurting our ability to build a reader base and network.
I know WP is providing a free service to many people, I get that features need to be updated, tweaked and changed, and I'm all for that. But how this has been handled smacks of disrespect for WP's users.
The bloggers here are a major contributor to WP's success, after all.