My thought, and hope, would be that the 'sale' portion of the announcement was/is just a way to let everyone know, all at once, that these buildings have been added to the game. And they will eventually make there way into the crafting recipes just like the other 2 or 3. - But its a new item. A good one at that. So it makes sense they would try to sell the new good item first and gain a little monetary bump.
I asked about why they only made these buildings for two of the five unit types; as im sure many others have. There is probably still my old thread on it somewhere in these forums. Naturally wanting the buildings for the rest of the unit types, but short of that, at least providing us an explanation as to why they chose not to include the others.
Never really got an answer.. but today at least there is new hope that they will become available.
Then i was left wondering why jsut different percentages boost. But that kind makes sense. Light melee was always my weakest unit and i generally try to avoid them if im able. Heavy melee would probably be my second weakest, tho i still have to use them a lot. So the fact that those two got the higher boost makes some sense. - I guess I was just surprised of the dis-balance acknowledgment. Inno does do a lot of balancing work. (which is hard, especially for military, i know). It just caught me off guard to see it addressed in that manner.
Im still happy to see the buildings tho, dont get me wrong. I really hope they become available.