I see that we have here three schools of thinking.
1. People that will equate benefits for all play styles so in the end it won't matter which path you choose. You could decide the last turns what type of victory you're going to achieve.
2. People that prefer to be able to build everything just when they see fit to the conditions of the current game play. Adjustment is key and wrong choices will make you fail.
3. People that want every play style to feel different, strengthen every strength, but with equal chances of winning. You can win with any play style or victory condition in mind, but at the end you are committed with that victory condition and others are unlike.
Let me illustrate.
People from the first group will give sources of culture for scientific civs and sources of science for cultural civs, gold for militaristic civs and improved defence for pacific ones. They want to secure some wonders for civs that are late so they can catch up. In the end, players do different things but they arrive to the same point.
People from the second group prefer to let the choice free. If they think they are going to need money, they will rush for the Colossus. Side effect is that tech leaders get first to every wonder.
People from the last group will secure the Great Library for scientifically focused civs, and Oracle for culture focused ones. But a level 3 ideological tenet should be as powerful as being technologically one era ahead. Being a diplomatic power should be a threat to everybody all by their diplomatic advantages (more friends, defence pacts, gifts). Militaristic civs get their advantage by highly experienced units and generals (and a weak AI). The problem is that currently nothing compares to be to technologically advanced.
Before locking wonders for play styles, we should decide if those wonders are to enhance the strengths further or to make up for weaknesses. All suggestions to the date go to enhancing strengths, and restricting freedom of choice.
Additionally, if a wonder doesn't get built in its time window, it could be opened for every civ, instead of nobody building it.