At lot of the special one-per-universe buildings are that way. They get no personal benefit from adjacency, and their benefit of having is the big bonus thing they provide, plus the adjacencies they GIVE. 

It does seem reasonable.  

On the other hand, a non-trivial number of the "one per civilization" buildings are somewhat broken in a parallel manner: they aren't the kind of improvement that they give adjacency bonuses for, so while they might get leveling bonuses themselves, they seldom do.  That is, the building is of type "Influence", but it only gives "Research" adjacency bonuses.  Since these buildings tend to be natural "hub" buildings, not getting back the adjacency benefit they give means they themselves seldom have few levels. 

 

Play Synthetic, and you get both in one: The Synthetic version of production hub gives an adjacency bonus of type Social Construction, whreas the factories themselves have the type All Construction. Therefore, if you build them, you're giving up a significant amount of production adjacency bonuses for the factories. As a result, I never build these any more: once the pop grows beyond 10-15B, any low level factory is worth more in terms of production than this. Plus you can't destroy it, so if you built it early, you're stuck with it!