I absolutely love the new adjacency ideas, but I 100% agree that they need to become "super adjacencies" because at the moment basic district will provide better adjacency bonuses than these wonder adjacencies.  If we're building in a city, we're also missing out on the hamlet-like benefits that a disconnected Wonder brings us; I don't think it would be unfair or unreasonable boost the wonders' tile adjacency bonuses to +8 or +10 for unconditional adjacency (e.g. "per adjacenct district"), or even +15/+20 for conditional adjacency (i.e. "per Market Quarter") because the wonder needs to compete with core quarter adjacencies and lost hamlet income.

(Aside:  I had the similar thoughts as yours on the Swiss Watchmakers back during the Together We Rule beta, and ran the math as well.  When nestling the Watchmaker inside a ring of market quarters, the benefit from getting a then-6 additional specialists didn't match the benefit of plopping down a regular district for passive bonuses.  In the end, they made the watchmaker a Market Quarter itself so it at least gains some adjacency bonus, and doubled the specialists.  The Swiss are great if you're entering Era IV with more pop than you can use, or if you're eyeing Singapore or city mergers.)