Would you be able to explain more about why you think that’s an advantage worth the additional complexity?
What is the basis for that expectation? Almost all of my payments with physical cash, LN sats, and bank credit are for less than half of my available liquidity (respectively: cash-in-wallet, sats-on-my-side-of-the-channel, and available credit); I would guess most of my payments are for less than 1/10th my liquidity. User-initiated stuckless payments should be convenient under those conditions, with no need for additional third party liquidity.
In the rare cases where I make payments that approach the limit of my liquidity—conditions where stuckless payments might not function well or at all—I don’t usually mind waiting longer. For example, I don’t want to wait more than a few seconds to complete a purchase of a $5 hot beverage but I don’t mind much that it often takes over a minute to complete a $2,000 purchase of airplane tickets on my current credit card (the bank usually requiring me to verify the purchase via text message).