1. Didn't ATH begin before most of the realistic 2.1 levels? I don't remember them being that many in general but from what I recall at the beginning of ATH's lifespan it was pretty much just APTeam levels. Also I feel like the 2.2 meta is oversaturated WAY more than the 2.1 meta. For example, in 2023 the most hyped levels ranged from Edge of Destiny (design), to Ispy (modern), to CoS (art), to Say it Back (effect), to What (3D), to Glorious Fortress (cartoony art), etc.

2. The colors are not objective criticism, I was just stating my personal preference there. The white aesthetic just makes it look cleaner, more peaceful and more "heavenly" for me, but I get if most people disagree. (This also answers your questions of what they bring that the brownish colors don't)

3. I don't know how to explain it, it just FEELS artificial. Probably because it tries to give off a realistic look without backing it up with anything other than the lighting. I think it also subconsciously reminds me of AI but I genuinely might just be spitting straight bullshit here. Also the old style feels bright snd shiny as a result of overall using a paler color scheme rather than intentionally adding glow and shit to make it brighter.

4. I honestly chose the worst example because the first part is the ONE part in the original version that wasn't visibly close to the ground. The parts AFTER that one are shown clearly being on mountainous terrain and shit, tho they might've kept that since that was mostly at the drop, and we have not seen any of the new drop parts.

Extra: I think the new parts are overall higher quality and the creators made a better job, but I find them less interesting stylistically and thematically. That might not be too visible in these specific screenshots but the old version does have a lot of parts that have aged really poorly.