#4: Keeping it Interesting!
It seems that the developers' thought process was: "We have a new mechanic. Policies unlock wonders. Where should we put them? Liberty gives you quick workers. The Pyramids give you workers. How about Liberty enables the Pyramids? Tradition is good if you want your capital to be big. The Hanging Gardens makes your capital big. Seems like a match."
How can you dare telling such a thing ?!? (and even thinking about it)
If Civ developers were even remotely working like that we wouldn't be playing so much (and discussing !) this wonderfull series (best all times, I play since #1).
Maybe it doesn't please you (some things doesn't please me also), but it makes a lot of sense to have done it that way. Policies are about differentiating your civ one way or another, having the associated wonder reinforcing this makes perfect sense.
After a while and according to experience some changes may be made by those devs (maybe the one you want !) to better balance the game. Who knows ?!
But anyway I really don't understand your point, it's what all Civ is about, synergies : having a bonus that reinforce a bonus that you already have making the combination of those bonuses more powerfull than each one of them.
And you said it's a "no brainer" making the game to lose some interest. There are many no brainers like this in Civ ! If you want to win culturally better of building Louvre, Sistin chapel, Internet,... The thing is that you have to plan for it, balance whether the ressources you'll put in it are worth it at that time and finally if you estimated that yes you want it, you have to get it first. Here is the interest ! So maybe you play at too low level for your skills and don't really need to think about all these questions, but that's what makes the game loose a lot of interest.
