Technicalfool: It's not "piracy". It's common sense. And DRM gets in the way of that, so I'm rather glad that KSP has none (and neither does Factorio).
nipsen: My point, more generally, is that it makes no sense that we should pay extra, and have inconveniences, for services only publishers think makes sense.
If we were to pay to support ecosystems and deployment platforms, then what we should get in return are structured releases designed in such a way that updates don't break the original files or inserts, don't crash saves -- and don't use the type of serialization schemes that are one step more advanced than the demo-example in visual basic.
What we have now is that we negotiate ourselves down to not having debilitatingly expensive drm systems, while still giving the deployment benefits of the system to the publisher. And hailing this as a victory. It's literally like this: "Yay, we did not get reamed up the bum by someone we paid money to! Success!". Does that make sense?
So when KSP launches 1.4, with basically no additional features or mechanics whatsoever - other than a specific launch-vehicle for an extra paid download patch - does it make sense that the publisher should be able to invalidate the installs of everyone who bought the game previously, to get them up to "speed" on the latest release. For, like explained, no other reason than to have people see Take2's paid dlc?
There are things you can do, but shouldn't. And there are things that you can get away with, but still wouldn't do anyway. And then there's the games-industry, where you do whatever the fuck you want, and have gamers worship the smell of your bullshit anyway.
Apparently the mission builder (not replicated by any mods, by the way) is no content? The extra parts are only a small part of the update, and I should know a thing or two about that.
The save files that KSP uses are not just serializing the contents of RAM to disk. Go and check the save format some time. It's more akin to JSON, and editable in Notepad if you like.
And there is basically no software that can guarantee compatibility from now on and indefinitely into the future. Bit-rot happens. It can be mitigated, reduced, but not entirely eliminated. Even IBM's mainframes with COBOL scripts running on them from the 1960s only do so because everything's wrapped in an onion-like series of VM and emulator layers.
And nobody's installs have been invalidated. This is GOG, where you can choose to update or not, and no games have DRM. The advantage is firmly in the consumer's hands there. If you're on Steam, and you have a modded install, why are you even running it from the steamapps location? Steam is known for autobreaking things with no choice.
So yes, there's a lot of shady practises in the videogames industry. That's why I don't buy a lot of games these days. But, I still have yet to see what any of it has to do with KSP or the Making History expansion. Heck, if you're like me and bought it a long while ago, when it was only available on the KSP Store, you get the expansion for free.