MCU-defined switch mode converters are great when:
* You need a special case of converter, no IC available at all, or expensive
* You need a surprisingly common case of a converter, but the IC designers have utterly failed to produce a sensible part, hence you need to Design-it-Yourself. For example, you need current limiting without entering an error state even though it's such a trivial and usual feature!
* You need the MCU there anyway, and using an MCU capable of being the converter as well costs less than using an additinal IC
* You have already designed a few, so you know you can do it, and don't want to take the risk that the commercial IC is revealed Broken-by-Design (does happen) - i.e., you trust yourself more than, for example, TI. If you don't know what you are doing, this is called "not invented here" syndrome. If you know, you are an expert. The former tends to lead to the second. Do it and you learn.
* You don't know exactly what you need, so the flexibility through modifying software is appealing for you.
Of course, in majority of cases, you don't need them. In my latest design, I have 9 standard switch mode converters using ICs, and one MCU-based, because only this one is such that there are no relevant IC options available (dual-phase synchronous buck 500W 48V to 25V CC-CV battery charger, in this case).
What comes to LED drivers, the market is literally saturated with the control ICs; LED lighting has been a big market for over a decade now. Yet I'm 100% positive many of these fail in their intended job, and those that do work always leave some gaps and corner cases where you need to create your own.