The difference is without subscription, I can be pretty sure the next major version will benefit me.
With subscription,the only thing certain is that the seller wants to do as little as possible to keep taking my money. This tends to result on product updates that benefit them.
This kind of shoddy, surface-level "incentives alignment" analysis can just as easily be used to prove the opposite: with the "pay once, then pay for upgrades" model, sellers are incentivized to never actually fix all the bugs so that you are always forced to buy the next version.
Except in the case of a natural monopoly (which doesn't apply to software) you can always switch to something else. Which means the seller needs to remain better than the alternatives.
You underestimate inertia, and the fact that the industry has trained people that they must pay continually. On top of that, the common practice is to make it sufficiently hard to get your data out of your system and into the competition's - even when there's reasonably priced competition it does a great job at adding to inertia.
With subscription,the only thing certain is that the seller wants to do as little as possible to keep taking my money. This tends to result on product updates that benefit them.