So when watching the professionals they are all getting their knee down as it aids them in working out how much lean angle they have left so as not to push the bike past it's limits.
Yes, anyone can ride equally as quick without getting knee down however they will not have a physical feeling as to how much they are leaning and therefor, could, lean the bike too far resulting in them dropping the bike.
To mention Rossi and the like, they all use their knee as a pointer to how far they are pushing the bike.
Obviously I will not be pushing the bike to its limit and am not making out that I want the knee down for any other reason than self gratification, however those that do race correctly all state that the knee down is safer as it allows the bike to be held upright thus allowing more acceleration out of the corners as the contact patch is greater.
I may be wrong but after reading racers testimonials that seems to be the common consensus.
