Once the norm for cross-compiling applications for MCUs, paid proprietary IDEs are starting to be outnumbered by free, open source solutions. However, the mere existence of free options doesn't immediately render paid options obsolete. The selling point of proprietary IDEs is that they provide the widest range of device support and require the least amount of attention from the developer.
Designed to work out of the box, the paid professional-grade solutions' claim to fame is saving developers time. These time savings will typically come in three main forms: unified environments for setting up an MCU, unified debugging environments, and vendor-supplied middleware, common across multiple MCU vendors.
Getting an MCU up and running is easier now than it ever has been, but once a project gets advanced enough that it starts defining specific memory regions...