Though it doesn't matter how skewed the deal is because the intent is that once you get their gold, you're cancelling the deal via DoW that same turn. You can offer every single one of your resources and all of your GPT, in the end, it doesn't matter.
I do agree though that it's pretty obvious this is "cheating" on your part. It's almost akin to whining about game balance when you rig the map in your favor everytime you play. Or somebody saying the game is too easy but they save/reload all the time.
Sure. You can do it and get away with it. Doesn't mean you should.
That said, I still agree these things should be fixed. However, If I ever feel like something I'm doing is an exploit... I simply don't do it. Which is why I never rush the A.I. They clearly aren't capable of fending off a rush in anyway.
In an ideal world, we shouldn't have to give the A.I. these handicaps. However, on the flip side, we also shouldn't exploit them either. Imo, finding that standard is up to each of us as players until things are "fixed" or removed altogether. There were plenty of systems I enjoyed from civ4 that I didn't partake in because the A.I. had no concept of their appropriate use ~ three easy examples; firstly, the two halmarks of BTS: Espionage and Corporations.
But more alike what we're discussing now; mass stockpiling units with city raider III to upgrade into rifles, and then stomp the world. It was very easy to get at least one city that could produce city raider 3 units... So you build them over and over until you get rifles, then upgrade to an unstoppable force. Sure, I can do that... but the A.I. doesn't have the capacity to understand executing a strategy like that. So technically, it shouldn't be done.
Additionally, I feel a lot about winning on Deity in civ4 was learning some of the exploits anyway. In this case, civ5 may be no different.