Something around 24" with increased resolution might be ideal for a lot of people. Around 20-30" away it comfortably fits the field of view without making cursor navigation into a huge issue. Even for professional use in a wide range of fields, ability to hit something quickly with the cursor helps quite a lot, and being able to do so without cursor acceleration is generally ideal. I'm not sure what they'll do in that regard. A 27" display covers a lot of users who need more real estate, but I've always felt tying display size/specs to the specs of the rest of the machine was rather limiting. If it's just a 24", it may still feel restrictive for some individuals, so I'm not really sure. I can say that a single 16:9 or 16:10 display can displace a lot of prior use cases where dual displays would have been the primary option years ago. The greater horizontal real estate on a single screen often provides better continuity and fewer ui issues across applications.
The OP's context is specifically gaming. Apple has never really optimized in favor of gaming. They just market Macs, and many of them are good enough for gaming. They are not as tailored for that purpose as a gaming PC, as they are not purpose built machines.
The 27" seems to large, imo. Look at it at the store over a couple of visits. Maybe the new design makes the 27 feel less overwhelming.
I'm trying to be less nitpicky, but this is another one of those posts that annoys me, as it sounds shallow (even if the person who wrote it really isn't). What matters is how it looks in use. In use the new design is identical to the old one. You're looking at a 16:9 27" display either way. The design didn't change the resolution, overall footprint, scaling, or any other element related to actual use. Surface reflections should look dimmer. That's about it. Its look as a piece of furniture has nothing to do with how 27" feels in use, even in the store. Once you position yourself to look directly at it, the focus on the screen should dispel the illusion.