You know, there are always choices to be made in playing a game. And if the players that have this issue are "billionaires" (in game terms, I'm assuming), then rebuilding them later shouldn't be an issue. I mean, power leveling GBs quickly has been a thing for years in top guilds...and even in some that aren't so "top". I don't see this as anything near a "must-have".
Unlike event buildings and GBs, there has only ever been one chance to get Cultural Settlement buildings. Which is why it's reasonable to replace some of them, but not so much with event buildings (which you can still get) or GBs (which you can just rebuild).
I stated earlier on another thread, that the restriction on building them again could be removed, giving everyone who purposely sold or deleted a CS building the chance to gain them again. It would be at a cost of their time. That would be a fair resolution.
If the boost to the Obs goes live, why would it be fair to those who built, leveled and then deleted it, for whatever reason, to not have INNO replace it at the very level they deleted it at?
As far as EB's that were later boosted: If the AD was actually random and the chance to gain all levels of EB's were available, that would be fair too. However, the AD is not open to random chance. I have not seen a Sleigh Builder for over a year. I saw them all the time in the past. When I decided to buy several and filled my city, they disappeared. Same with the Sentinel Outpost. Once I bought several and filled my city with them, they also disappeared. That is not showing a random chance. It is definitely (in some way) tied to or dependent on what I have, not on what I want or need. Same with a few other items. I see the same stuff that I have no need nor desire rotate through regularly. Some I buy for CP's but then sell them back. However, they keep showing up all the time. I am talking older buildings than the SB and SO. Coincidence? Possibly. However, not likely. Again, if it were completely random chance, that would be fine. It might take some time, but it would be possible. Regardless, by the time you get all the levels, boosted or not, they would probably be outdated anyways. So, why not just return them if they were boosted after being removed?
The free return benefits me, so this isn't me complaining because everyone else benefits. I sold a few CS buildings myself. I am just pointing out another issue where INNO is either being hypocritical and partial or just did not think this through very well ahead of time. I just do not trust that they have a very strong brain trust that makes these decisions. Time after time and issue after issue proves that out on a regular basis.