I think it's a touchy issue unfortunately, one where there's definitely going to be someone unhappy with either option. I agree that having it on a separate page means people are less likely to look at it. However, Cohost's blurbs when you sign up say that they promise to not sell ads, which I believe was their reasoning for making it a separate page (because while they are in fact still selling ads, they're at least not forcing anyone to look at them). This does make them less effective ads, but you're kind of in trouble either way. Either you have ads that people may never look at, or you have ads that people who very much signed up with the promise that they wouldn't be shown ads are now being forced to see. It gets even trickier when you consider Cohost Plus users, because while they weren't promised that Cohost Plus would make the site ad free (because it already was ad free), there's an expectation that a site you're paying for shouldn't be showing you ads.
Basically I think both sides are right here, but both sides are incompatible with each other. People who want to see the artist alley stuff would probably rather not have to go check a separate page for it, people who want to not see ads like they were promised will not want to see artist alley on the sidebar. People who want to pay for their ads to be on the site would get larger benefit from it not being on a separate page probably, but it would require Cohost essentially going back on their word from before. It's a rough situation. It's possible that you could make this an opt-in feature, but then to some degree you have the same problem Artist Alley already does where you have to manually make an effort to go look at it (the only difference being that in this scenario you only have to make that effort once and not like...weekly). That's probably the only middle ground solution here where you could offer this without alienating a lot of folks.
I think the opt-in is kind of what I'm gesturing at, basically what the userscript allows but natively integrated.
Kore M
Artist Alley is great, but having to go to a separate page to see it is a bit unwieldy and disencourages actually going to it. Having it on the sidebar, like the userscript https://cohost.org/blep/post/5752032-quick-userscript-re does, would be a great option.