I notice a lot of the guys arguing that not giving the outside guy racing room is proper overtaking are karters. Whether or not that is legal in a kart depends on the track, series etc but generally, karters drive like that because it is allowed and in some classes, the only way to pass. It is significantly less likely that that would be allowed in club racing in the US- stuff costs more, so racing room is pretty much given. In the SCCA at a regional race, if someone held the outside and there was a wreck, the inside guy would get DQ'd or even lose his liscense for that! Ok, maybe not at the runnoffs but anywhere else, certainly. The point I'm trying to make here is that in real racing, it depends on the series officials and drivers what is acceptable and what is not. What would fly in F1 might not in ChampCar or Grand-am, as the latter two have cracked down on "avoidable contact". I think a good rule of thumb is that you can make somene hang a wheel off, but any more than that is excessively aggressive.
I would put Senna's 100% comitted pass in that category, because it leaves no racing room should his opponent refuse to yeild. I think that if you can get along side someone like that you will likely pass them in the end anyways, so leave them room.