I love Rexx and have used it extensively on IBM mainframes and PC's way back. That said it seems like the ecosystem has moved away from the the types of integrations where Rexx was strong. On IBM mainframes it was always the tight integration with things like CMS and XEDIT that made it great.

If you're using Rexx today on e.g. MacOS or Linux I'd be interested in hearing how that's working for you... My goto for scripting these days would be Python in those environments (or bash).