I built a tool that helps with copy pasting code into chat UI called 16x Prompt.
It is used by quite a lot of people. So the problem is definitely there.
The app supports API integration as well. From usage stats, still there are more people using the copy pasting flow instead of API flow.
I suspect it is because people are already have a subscription so they can basically use that for free, versus via API where they have to pay.
With that said, Cursor's $20/month unlimited usage is really too good to miss. I will wait for it to end soon.