The UI for curl is awful (--request to change the method??) and wget's is only slightly better, but they do have the advantage of ubiquity, and it's often useful to email/Skype complete curl or wget command lines about the place to explain how to use an API, or demonstrate problems.

(e.g. Stripe and others document their API in terms of curl commands: https://stripe.com/docs/api.)

I do wish the curl UI was better, but I can't see it being trivially replaced. (It's a similar issue with git: bad UI, but every git question and answer is described in terms of the CLI, so even if you prefer a GUI client, say, you still need to be able to formulate your problem in CLI terms for anyone on stackoverflow to understand you.)