I don't know how Etsy chooses FP treasuries. Someone here can probably answer that question.
Do you contact the shops you include in your treasuries to let them know they've been featured? Do you promote the treasuries on teams, FB, a blog, twitter?
My treasuries get so-so views but I always notify the sellers I feature and promote the treasury on the team I'm most active on. It creates a ripple effect of views because the featured sellers and my team members share, promote and favorite the treasury (favoriting causes it to show up in their followers' activity feeds, which means more people see it).