Swear I'm neither of those things, but you're talking about the system tray as in that little bucket of icons that sits in the lower-right of a taskbar usually?
This seems like it'd fall pretty neatly in the "you use it, so you think it's required basic functionally; other people don't, so they don't care about it" realm. I do not miss the bucket. It doesn't seem like awesome functionality (to me) to have to access application features through a bucket of tiny icons instead of the application itself and to be unable to access those features in the application.
I can see how frustrating it'd be if there's something you like to use or have to use that only works if it can be in a system tray, but it's not a ubiquitous feature requirement across all applications, so maybe GNOME is for people that don't care for apps that require this and all the other mainstream OS options are for folks that do? Man that's an annoying sentence to read; no wonder people get so angry about what seems like pointless minutiae.
I assume I dislike it because my work machine (windows, no choice there) always has about 30 things in its pointless icon bucket that can't be closed by a basic user and do nothing beyond cluttering the taskbar and getting in the way. I get nothing out of a bucket of icons that exist only to silently scream "I'm running in the background still! Just in case anyone cares!" Not having to see that crap on my personal machine is a relief rather than a frustration for me.