I think the bigger budget for ROTF compared to the first movie was to blame, Bay was constricted with the amount of fighting and robot scenes in the first movie therefore more people and character development was needed, so here came a bigger budget for ROTF and he went nuts!!!!
No real story, less character development, but as many explosions and robots as possible!
Transformers 3 will most likely have even more explosions, robots and less of a story than ROTF because bay will have an even bigger budget! Hopefully there will be some cool characters aka unicron so we can have an insane toy to purchase!

So a credible and faithful movie is unlikely so therefore i want to see as many transformers and explosions possible with more combiners, unicron and DINOBOTS or BEAST WARS robots lol

well thats my 2 cents lol