I’ve actually gone back and forth on this a little. I’ve owned pairs of stereo amps convertible to mono. Also I’ve owned some "pure" monoblocks. First of all, creating a mono side out of a stereo amp by "bridging" (as switchable SS amps often do it) is generally deleterious to sound quality, and runs the amps much harder / hotter (that’s why SS amps yield up to 4x as much power per side when bridged). But even on the amps that don’t achieve mono by bridging (e.g. tube amps parallelizing on OPT’s) - certainly the mono configuration sounds more "perfect": better dynamics, slam, clarity. Overall just more pristine. But when you don’t need the extra power, sometimes I wonder whether the Stereo configuration is somehow more musically coherent for a good music session, and if I might actually prefer that.
It’s hard to beat a really good, musical, and "powerful enough" stereo amp - and I appreciate the simpler configuration.