I do not see Flexibits as evil and I do not blame them for anything. It is their right to do whatever they think is good for their business. It is just that Fantastical is not for me any longer. And that is fine.
Fantastical started in v1 as a menu bar application on MacOS. You were able to purchase v1 for twenty bucks (?) to enter stuff into your calendar using natural language. Just great back then. 
Then they released v2, they doubled the price and basically changed Fantastical to a full-fledged calendar app. I missed out on the upgrade pricing because I thought that it was not worth it to me because I just am not a calendar power user. After about a year, I eventually bought v2 because I thought that I needed it anyway (yeah, I know). 
I eventually bought the iPhone and iPad version. I really do like the iPhone version. I have been using it regularly. Regularly means maybe once a week. Most of my appointments come automatically through web calendars (ICS). I do not enter those. Occasionally, I have to enter appointments, but it is not often and sometimes I use Siri or Shortcuts.
With Fantastical 3, Flexibits really seems to have released a calendar app with many features and many new ideas. I absolutely get that they have increased the capabilities of their application far beyond the feature set of previous versions. They basically have created a completely independent solution even with a server-side backend.
Flexibits thinks that their application is worth about 40 bucks per year. If I used Fantastical daily and maybe even more often than that, I probably would agree.
What I am not entirely happy about is the way how they spin it: v2 users do not loose anything with v2 (that is their message at least in the App Store and in the app)? I disagree. Apart from any features, they loose the ability to keep using Fantastical in the long run because eventually there will be no bugfixes and no support (“existing customers … will continue to get bug fixes and support for some time to come”) without paying 40 bucks per year. I totally get that you cannot provide everything for free. But there is a difference between paying 40 bucks every two to three years for a new app (I am referring to their blog post) or to pay 40 bucks per year for a subscription. I do not say that paying 40 bucks per year is too much, if you are a power user of Fantastical, but it is definitely too much for me. Text Expander, 1Password and the Omni Group did solve this problem with existing customers more elegantly, I think. Each of them differently: they offered lifetime discounts to their subscriptions or they provided their customers with options other than a subscription.
As a developer, it is totally fine to say Fantastical is 40 bucks per year now, and to say that you need that amount of money from now on. Just stick to that message, because basically that is what is really happening right now. Yes, as an existing customer you can keep using Fantastical for the time being, but if you want to keep using it, it is 40 bucks per year in a subscription and nothing else according to the Flexibits blog.
Again, it is ok. Fantastical has evolved from a little tool for entering appointments into Apple’s calendar solutions to a full-fledged calendar app with a server-side backend. This is a totally different app for a different type of user when you compare v1 to v3. Which means that Fantastical might be the wrong app for the user if the user has not changed in his or her needs for whatever a calendar app needs to do. Again, that is fine. And that is why Fantastical v3 is not for me.