I love the concept, but I use Patreon to provide a supplemental income to my freelance work. (I would love for it to replace it but I’m not there yet.) Offering annual memberships would reduce how much I receive every month. (Yes, I realize I would still receive the payments, but I would have to hold on to the income and divide it out each month, which makes it dangerous for me.)
I would LOVE the ability to offer annual memberships, but ONLY if Patreon would divide up the payments. I realize this is probably not likely, but one can wish.