I have mixed feelings about this! On the one hand it’s always nice to simplify and I get how it didn’t make a ton of sense to have categories as its own sortable column (didn’t even realize it had been sortable, actually!)
On the other hand I agree with the several comments that the new layout makes the topic title column feel a lot more crowded than it did previously. (And on a desktop-sized screen, results in a lot of negative space in the center so feels kind of unbalanced).
My main complaint is it makes it harder / just visually more jarring to quickly scan the list of topic titles. I think @ralph1 is spot on about that. To help mitigate that, I’d definitely be in favor of both de-bolding and lightening the category names.
Personally I think I’d prefer some kind of “pseudo-column” with category still displaying to the right of the topic title, just without a column header (particularly if the box style is still an option…the emphasis / info hierarchy is really out of whack in that case). But I think any de-emphasis of categories will help a lot in bringing me around on this change