I think there is a problem, but I also think people are over-reacting a bit. There seem to be a sizable camp complaining that the early game has changed, and the old G&K builds no longer work, and a sizable camp saying that everyone who thinks there is a problem belongs to this camp, so I hope everyone can ignore people in both of those camps, while we work out what the best way to fix things is...
The early game lack of gold does hurt the AI, but it also hurts human players somewhat. Early-game pushes are almost impossible, and there are more efficient ways to play. What we need to do is make early-game pushes *viable*, but not the most efficient way to play all the time.
Ultimately, I think the problem is early-game unit maintenance, and *NOT* the AI. Once you have 4-6 trade routes, and each of those is pulling in 20 GPT, it isn't a huge issue, but in the early game you don't have the economic flexibility to even float a standing army, let alone an offensive force which includes siege. So it isn't a problem with the AI, but rather with the mechanics of the games which make it so early-game pushes are *NEVER* a viable strategy.
There are two possibilities I can think of to fix it:
1) Reduce early game city strength significantly, and make the AI more likely to go to war [I don't like this option overly much, as it harkens to the days of old where you could launch warrior-rushes against cities]
2) Give a small number of free units for each era. I was thinking 3-5 free units in the Ancient era, 6-10 in the classical and medieval eras, and 3-5 free units in the reineccance. This way Builders (like myself) can build a tiny standing army, and not have any economic drawback, while people who want to launch an early rush can go over the cap, take an economic drawback exactly proportional to their offensive capabilities, and (hopefully) capture some cities, or hurt a neighbor enough to make it worthwhile.
Disclaimer: I am a Prince player, and haven't managed to win a game at King difficulty (the reason being that I could not cope economically with the G&K early-game pushes)