The lack of colour and features in RBY is what makes me less likely to play those games. It just isn't as engrossing, because of how blank it is. It's like it's lifeless and dull, and I don't like that.
I'm replaying Crystal right now, and I actually like it even IF the designs don't give any distinction; it does allow my brain to think and ponder creativity as to what they'd look like - and the addition of colour and improved sound help establish it.
I do sort of miss the generic environments I grew up on, but I've moved past RBY. Fr/Lg exist and those are better in my mind because they're not going back too far. Some of RBY's drawbacks are just too much for me to overcome in my age, and playing Silver before them really is something that influences that, I think.
I do understand what you're saying and only partially agree with it. Some of the current designs are somewhat overwhelming, but they feel so much more real. The earlier graphics engines create further cases for imagination, and ultimately, I feel that this is why I'm playing Crystal over SoulSilver. SS just doesn't have the same charm to it...