The situation is not totally clear cut... but...
Ultimately, MC20 would still supply the Microsoft EPG data if Microsoft had not changed their format.
In a similar way, Youtube frequently changes the format, and one could not expect that JRiver would update MC19, MC18, MC17 and so forth every time they do so.
SO, I think it is reasonable to say "We have to spend hours of our time to make this change to reflect the action of third parties, so it is part of what you get by updating."
And, as mentioned by posters in the "EPG" thread, across the world, EPG data is very rarely available for free.
(As far as not wanting to upgrade to MC21 due to potential instability, the same argument applies to every update and feature that will be part of MC21. While some JRiver MC versions do break some features, they rarely create any general instability - and when they do, the update is pulled from circulation and quickly fixed.)