Yeah, cases like that are nice for improved cooling.
Broad cases like these may still seem unusual, but they do have their advantages. Primarily, PSU is moved to the side, which leaves unhindered air flow intake onto the GPU - which is quite a biggie in itself.
Fans on the side means (among other), that the noise from there goes away from where one sits. Or if one wants the rig to be as quiet as possible, then it is also about custom cooling for the GPU - and a case like that is useful to set it up, leaving the option to have i.e. AiO for the CPU as well.
Either way, with GPUs and partially also CPUs pushing the wattage, and NVMe SSDs also needing some cooling, it does need space for intake/outake fans. Which is why I went with the case I have, as that offers some options in that regard. Tempered glass is not that a biggie for me. It is nice to be able to see though, when a LED on the mainboard pops up - and AiO for the CPU I will eventually get me one showing the temperature.