I agree with this. Playing out the millions of years between the Ark/Nemesis taking off and when the Cybertronians awaken on Earth would be a great opportunity to flesh out that massive gap a bit, and possibly come up with a reason why the war kept going on in the absence of the two factions' leaders. Plus, no humans taking up focus is always nice, though humans don't have to be totally absent to not hog up time. That G1 RP I mentioned earlier did incorporate humans, but only in a way that would bolster development of the Cybertronian characters, such as when Spike was giving one of my OC's a new paint job after his repairs, or when a group of Decepticons raided a military base to find a psychic human.

Also, would a character yanked from another dimension somehow be fine? There'd be no screwing up any timelines because of this, and I can provide a nice explanation in the history for how he got into our dimension.