If done right var could be awesome but it's flawed right now. Also there is no more "we will give you the benefit of the doubt". There needs to be a little leeway.
About the rule: someone suggested to state the rule somewhere so we do that soon.
At least the VAR people should admit that there is an inherent margin of error in the technology (camera framerate, image resolution, blur..), and offsides calls should only be made when the result is outside that (somehow quantified) margin of error.