I would counter that the Mermaids Paradise is definitely not only worth placing, but it is also worth keeping. I would
never delete mine.
This is why:
In my chapter, a fully upgraded Marble factory produces 3,784 marble per 3 hrs. Most people will not be resetting their marble factories 4 times in a day, because they have lives. But let's say I did. 4 x 3,784 = 15,136 marble. To produce that marble I have to pay coin and supplies. The Marble factory gives nothing besides Marble (no Population or Culture), and I have to pay for the production. The building is also larger than the Mermaids Paradise.
The Mermaids Paradise is 4x4, which is 4 spaces less than 1 Marble factory.
It provides Population, Culture, and a person's T1 boost from the get go. As it is evolved, it provides additional T1 (Boost +1 Stage 3 & Boost +2 on Stage 5) and at Stage 7 it also gives an Ancient Knowledge 3 instant. Now about the goods.
I have a Lvl 10 and it gives me:
9180 marble
8670 steel
8160 plank
Yes, that is less Marble than four 3 hr runs. However, if you add in the additional Steel and Plank you get a total of 26,010 goods. That is far more than you can produce in one day, in a smaller footprint.
I agree that I think Inno should allow Evolving buildings to be transported into Inventory. I wish they would. They probably will tell us they can't due to coding. I don't know. It would be very nice if they could work it out. I don't expect, however, it's ever going to happen. But what I do with the evolving buildings I choose to have in my city is create an expansion just for them. Then that building is "paid for" in my mind. I don't have to worry about whether I want to use that space because I know that space is allotted to that building. If a building is important enough to you, you'll find the space to keep it.
That's my "IMHO".