Compiling is compute intensive, but typically you can wait a moment while it finishes. Compiling is NOT as right-this-instant as Full-Motion Video, unless that is what you are developing. Swift has lots of added Libraries, so your code gets BIG in a hurry. But the tools allow you to MAKE only the modified files.
Your RAM and minimum disk sizes look reasonable. NOT smaller on RAM. You can add as many external drives as you like.
If you really need portability, you pay dearly for that set of features built in. Can you live with a built-in keyboard placed for portability, not for comfortable use? Also consider that the computer is optimized for Light Weight, not for heavy all day use. If you are immediately bypassing most of those MacBook Pro features or if you are closing the built-in display, the MacBook Pro is just more expensive, not more useful.
You could also consider a Mac mini, or also consider MacBook Air. The downside of moving down the spectrum is that the low-end models support only ONE external display, (two if you count the Internal display, or first display on a Mini.) The compute-power is excellent in every model, unless you are doing high-end computations like 3-D wireframe models and shading, or modeling akin to airframe stress analysis or weather forecasting.