Those tech changes are mechanical - they don't have anything to do with content. It'd only be the same if you lost access to the T-34/85 model.
Then make it precision strike or female partisans if that will make you not miss the point.
Balances changes are fine but if the game is sold piecemeal then players shouldn't lose access to particular pieces of the game through updates. I'm not sure where you're getting this straw man from.
Losing access to features and mechanics I think are acceptable as part of balance changes, but not losing access to unit types, especially if those unit types are still available through premium content.
Thats why war spoils are there.
You're not losing access to anything.
You get it by different means.
And its not like it was taken away and nothing was put in its place.
By extension of your logic you should pay to relic additional euro/dollar after installing the patch, because now you're getting premium content for free.
In short: your argument makes no sense.