I absolutely love that more clients are including WoT these days. That said, not all are, and reading from WoT relays gives the user the benefits of WoT without being locked into using clients that provide it.

Also, WoT within clients is typically limited to the particular "logged in" npub's WoT. Meanwhile, I can use a brand new npub that follows no-one at all, and I can browse a WoT relay's feed on Jumble, leveraging that relay owner's WoT to still see content I care about, free from spam. Or I can use WoT relays for my public inbox relays, even though I haven't built up a social graph on that npub, and I won't see replies from spammers, but I will see replies from a large number of legitimate users.

So I still see a lot of use for WoT relays, despite clients adding most welcome WoT features, as well.