Whilst I agree with you for writing queries, the gui tools provide some nice tools. I haven’t used postico but I regularly use sequel pro and the ease to write a query and export results via csv that non technical people might need is a great feature. I’m sure there is a way to do it in command line but for me I find it a lot easier as I’m not a db admin.

Also gui tools are really useful for visualising content in tables with a lot of columns.