Right now there’s only a toggle for each category, so if you want to enable all you have to click every single category, and there are quite a lot.
There are good reasons to want to search for all affixes. The main one for me is when I want an item of high quality, but can be flexible on what particular affixes it has. The way to do that is to enable all affixes, and in the advanced settings set the minimum sum of affix tiers (e.g. =>10). There’s no other way in the game to achieve this effect.
As a side suggestion: let us filter for forging potential. This gives us another way of filtering for high quality items.