I bother because it gives me a single banjo on each side of the head and an easy way to connect an oil pressure gauge.
Plus I would rather not have an oil line crossing over the top of the head which can be hard to route without touching things it shouldn't touch.
There is no other advantage or disadvantage that I know of.
I do feed the oil into the left hand side of the head as it is a known fact that the left cylinder tends to run slightly hotter than the right. Maybe because the crank is fed on the right side -I don't know.
I do know that the drilled spindle modification has been around for a long time -It's not my idea. But I have always done it both on my racebikes and my streetbikes and and a lot of other peoples bikes and never seen any bad consequences because of it. Jim