the reason that all gundams pretty much have the red blue yellow color scheme dates back to 1979 when the original mobile suit gundam aired. originally, the gundam was going to look like this">http://www.mahq.net/mecha/gundam/msv/rx-78-3.htm[/S</a> [&lt;---if that link doesnt work, its pretty much an all white gundam with a couple red details](with a few minor differences, sorry i couldnt find the real lineart for the proposed first iteration of gundam), but the color scheme was changed due to bandai's request for a more "toyetic" design. as an aside, "gundam" was almost called "gunboy", but the name was taken already, thankfully. oh also the original ookawara designs for gundam and zaku had a more 'knights armor' look to them, damn, i wish i could find that lineart!!!

Edit: actually back in the day bandai didnt have the lisense to gundam products yet, many companies made gundam merchandise including clover and popy among many, many, MANY others, thusly the blame for the decision to change the color scheme for gundam falls squarely on the shoulders of sunrise execs hehe