I tend to get a little annoyed about the offsides too.
If I spot someone offside nearby, I tend to run at them from dummy half, Terry Newton style. But they inevitably just tackle me anyway and don't get penalised. I think it's more down to the fact any offside AI player in the game tends to get back the 10 before actually making contact, rather than the computer referee being against you
Whereas when you control an offside player, you don't automatically go back the 10 (and manually going back is very flaky to be honest). I tend to try and take control of the marker every time to avoid being constantly offside (as then the computer takes control of the defensive line and gets them back).