But users don't want to do that legwork. I'm way more apt to use a product that, from the get-go, gives me what I want and then allows me to expand on that.

Designspiration thumbnails those images so small, it's impossible to just browse and tag without needing to click into it. That's my main complaint with most if not all of these services; I shouldn't have to click to see it in its full glory, and often times, the details get lost at that size and certain works are inherently at a disadvantage of being seen because of it.