-M for Method
-B for Body
-RH for Request Header
you know, so you only have to know the first letter and don't have to remmeber arbitary flags?
I know that it is not that easy, but unix tools do have the problem that often the flags don't make sense on the first glance.
-d for data
-X for execute
There was a reasonable attempt at this already. There are going to opinions on either side. And through regular use the flags would become muscle memory.
Should you be sending HTTP requests to something without knowing precisely what you're doing? httpie just sorta assumes from your arguments what you're trying to do, and for me it has often been wrong. Probably works OK if you have a mostly read-only API.
EDIT: Depends, most of the time I use standard JSON Rest apis, there is not really that much to misassume I think.