The darker and at the same time warmer colors are something I like about that era - it's cozy no matter what is on screen.

The lighting makes a huge difference, I think.

Also the character designs, well said from the videomaker. The clothes, hairstyles? Modern shows rarely bother, except with gimmicks. Say Hitori Goto a.k.a. Bocchi the Rock - pink themed outfit and hair. It sticks out. The rest of the character design is fairly average, but she is still easily recognizable.

I have never watched anime until a few years ago, but I tend to mostly stick to older shows (even if I kinda slowly ran out) for no real reason than me liking my escapism a bit outdated - no need to be watching anime on American children''s television in 2003 to like shows that were released 5 years before that to this day.