I joined Sept of 2009 so I guess I'm an oldie too.
I really miss the old ways of trading, even though people took advantage of others back then, I honestly feel as if it's worse now. After the end of the LIST system, everything just went haywire. I liked the rarity system we had back then. It was simple and easy.
But what I miss the most is the quality of the lines. We had limited lines, and it really stretched the artists imagination to come up with interesting and wonderful concepts each month. I really miss that. Don't get me wrong, I like some of the new lines too, and more pets are fun, but I honestly feel like I would rather have higher quality design with fewer pets each month.
I only collect pets I like now, because it's impossible to collect every pet. I keep about 1/5-1/4 pet outcomes a month. Everything else just goes into trade fodder. I'm a CS addict so I'm not going anywhere, but it's kinda like, OH...yeah... new month... guess I gotta check the adoptions. Where as before I was on my computer waiting for hours for the new month drop. Guess that's the price of success. Usually happens doesn't it? You find something awesome and the more people that also find it, the less appealing it becomes.