I can see both sides here too, mainly because its not very clear on their product page when you need to pay for a new version. Also consider some products are sold as "lifetime" and some as "Subscription".
With Start11 being Lifetime, and even saying so in the Start11 v2 upgrade FAQ thread. "Lifetime" would seem to imply that as long as Start 11 is still an active program, one should get updates free. And I can see why some might be caught off guard, and upset.
BUT They do have this on their web site -> https://support.stardock.com/space/SHC/1330774031/Maintenance+and+Support+Policy#New-Version-Product-Releases
New version product releases will be designated by an increase in the top level release version number. For example, when product version 2.xx has a version upgrade the new version number would be 3.xx. New version product releases must be purchased. Discounted upgrade pricing may be available to owners of previous version levels.
That statement (and the previous section on that same page) covers this exact situation. Start 11 is going from v1.x to v2.x, so therefore requires one to purchase the new version.
I do wish they stated this more clearly on the product page for Start 11, as I saw no mentioned of it there, during check out, or on the invoice I received.
All of that that being said, the current "preview" pricing at $1 off for NEW purchases, is very reasonable. And I just looked at the upgrade pricing, its even better. While not a free upgrade, the upgrade pricing is well worth it.
Now maybe I feel this way because I've been using Start11 since I purchased it in September 2022, so I am definitely getting my monies worth, and this upgrade fee is not going to break the bank. Maybe I'd feel differently if I was only using it for 2 or 3 months? I'm not sure. Again, the upgrade price is very attractive, and the initial purchase price wasn't outrageous either, considering how much more usable it makes Win 11 for me.