Nobody is being forced to move to Studio - the Wix editor is sticking around 
But correct, if you’re looking to use the features that Studio has to offer, you’ll need to rebuild.
In regards to the increase in Premium plans, you should have received notification about this well in advance, as these changes began before Aug 2023. For example, one of our forum topics about this - New Premium plans for the Wix Editor - EU & Other - there’s also been communication outside of the community, via email etc.
In most cases I’ve chatted to people about, they originally bought their plan at 50% discount, and are now renewing at full cost, along with the additional price increase - hence the comparatively large difference in cost.
Studio and Wix Editor are designed for different needs. Studio is built with agencies, freelancers, and enterprise users in mind, while the Wix editor is built with self-creators in mind
While a lot of the discussions and announcements in the community focus around Studio (as the community primarily focuses around agencies and freelancers), there are still updates and releases for the Wix editor.