When you pay upfront, the dev is not incentivized to try and keep you. So the product gets worse and worse until it dies.
If you pay overtime, the whole game is “how can we make this person love the shit out of this thing for as long as possible.”
This is not true.
When you pay up front, the developer has an incentive to make the product right the first time; instead of releasing a buggy product because it can always be patched later.
In the pay up front model, if the initial product is crap, then nobody buys the next version. That is the incentive to release a quality program the first time around.
Then the developer has an incentive to make the next version so much better that people who like the first product will buy the new version.
If you pay overtime, the whole game is “how can we make this person love the shit out of this thing for as long as possible.”
No, if you pay over time, the whole game is "how can we keep this sucker on the hook and milk him for monthly payments for bug fixes and things we should have done the first time."
For example, millions of people pay repeatedly for WordPerfect from version to version for decades because it just kept getting better. That's how it was done until very recently, even with operating systems.
"I know! Let's add every feature and bullet point under the sun!"
If I ever get around to releasing one of the various projects I have, it will probably use a tip jar.
But otherwise, why should you get access to all future updates and ongoing work?
I think Sketch has a good system - you pay once and you only have access to that version forever (bugs and all). In order to update/get new features, you need to pay again or have an ongoing subscription.
Of course it is better for the dev to sell a subscription, but having to pay when new versions releases is for the customer the best option.
Hint: you can charge for upgrades without forcing them down your users throats.
Because a norm has been established in software where you can charge for what in physical goods would be considered a defective piece of shit that should be recalled asap. This is beneficial to software developers and is predicated upon the concept of free updates.
I can't tell if it syncs data with my other Apple devices, but if it does, it would be great if it had the option of doing it through iCloud instead of through some proprietary untrusted service that I have to create yet another account for. (I' looking at you, Panic and Junecloud.)