Hi, Kimo. few reasons. Enough to think about in life without remembering to go into Paypal and edit out recurring payments. My credit card statement is long (three pages monthly), and I'd likely miss it. I don't want to belong and pay for anything forever, or by spotting something that has already been paid by Paypal and then trying to recoup the money--life's too short. I don't want to allow access on a recurrent basis to my Paypal account to anyone or any organization (and that's what signing up for recurrent payments allows, legally), I belong to at least six forums, from kayaking to hammocking (hammockforums.net) to writers/authors but none have only a recurrent payment system (most send a blast email asking for a renewal), so that's how I handle it.
That said, I believe firmly in owners of websites doing what they feel is best, business-wise, for themselves. They garner more revenue from recurrent memberships, then great. They weigh in, I'm sure, that a certain percentage of people feel as I do, and they determine for themselves if it's worthwhile to have only--and the key word here is only--recurrent memberships. Maybe there's 25% of forum users out here who feel as I do, and they'd be losing a ton with the policy. Maybe I'm the only one, and they'd gaining from having everyone renew, whether they thought of doing it or not (it just shows up on the credit card, bang).
I answer because you ask, Kimo. Nothing more, and not telling UU how to do things.
I do like the Pono, but getting used to tenor with my concert sized hands--well, the jury is still out on that one. lol THanks, man.