I think there are plenty of options for great maps to use for seasons; there's not really a need to recycle the same ones. I think it's kind of a fun extra to stop by and see what map is being used, so I'd be in favor of seeing new seasonal images.
The only thing that comes to my mind though is that they might get kind "lost to time" if new ones are chosen every year, and I kind of would want to see some spot on the site that mentions what the previous background maps were.
I already can't remember what any of them were other than the Nemo one, and that I just remember because it took me so long before I found where it was from.
Do you also like the background images for the individual atlas pages?
Yes! This is the greatest addition to the site behind doubling the random map sets!
And I find the choice for what map is being used for each console is just absolutely perfect. I loved opening up various pages for the first time and thinking 'Of course it would be THAT map!"
Except for the lack of a Metal Gear background on the MSX page; that needs to be fixed. Also the lack of a Rusty background on the PC-98 page, but that could probably be blamed on the lack of Rusty maps to begin with. (But I guess that's a different subject.)