What would you need to know in order to see DotM? The only MAJOR plot points I could think of were: Why is Megatron alive? and When did Optimus get the Matrix of Leadership? Anything else? I really couldn't think of any other major plot point that would require explaining should someone skip RotF and go straight to DotM from TF1. And considering that the overall movieverse plot gets confusing if you consider what happened in RotF and DotM, if you knew these couple of things then you could theoretically skip it.