A yearly banner contest? The premise isn't bad at all, but having the winning entry of a contest that happens only once a year displayed
only for a single day sounds excessively disrespectful. I'd hate to be treated that way, so there's no way I'd subject any member to such a treatment (unless said entry totally bothers us in some way, in which case we wouldn't display it as the forum banner at all).
Actually, we've long considered having a similar contest. Long before the
Symphony skin was even born (it's been almost two years now). I'll give you the end of the story first: like most of our plans and ideas, it simply got shelved along with the rest of them as we have our hands too full with other matters. As for the details of the contest (as we had it planned, anyway), we had pretty much calculated the views both of you expressed as well; in particular, the part about us staff having the final veto as well as concerns about the banner looking good.
We had planned to lay out the groundwork for the entries. We were planning to have a fair amount of restrictions, including things such as who (as in which characters) had to be present in the banner, what game―suffice it to say that anime characters wouldn't be sanctioned by
Checkmate us, unless they are based on eroge―they came from, which artist(s) illustrated the artwork, what theme the banner should represent, what general colour palette had to be present... things like that. We had even thought of making a certain amount of banners and then have members choose. That way, whichever won, it'd be something that had gained our approval beforehand.
So, yes, in one word: restrictive. On the one hand, we wanted to make sure that the most prominent part of the forum that appears on every single public page was something we'd like to look at. On the other hand, we didn't really feel like making a context with overly cumbersome restrictions and guidelines. It'd feel like we were trying to take advantage of members to work for us instead. Just like that, the idea slowly faded into obscurity.
Also, the banner in and of itself
does need to have a fair amount of restrictions and considerations. For example, take a look at the base groundwork for the banner image:
The base dimensions are 1920x300. See all those vertical lines and colour differences? They denote different widths: 1600, 1440, 1366, 1280, 1024 (as shown on the layer list). Yes, you guessed it right: standard screen widths. While the banner is meant to be best viewed on 1920px-wide screens, we also had to consider other screen sizes (sorry, 2560+px screen users!) to make sure everything within the central focus of the banner is still present even on small screens.