Q:

What's the point of removing the excess oil after lubing the chain?

There is a very strong point in bike-mechanics culture, which I've seen in very competent answers here, too, to apply one drop of lube in every single roller of a clean chain, and then (!very important!) to remove as much as possible the excess lube with a dry cloth.
I am aware a "soaked in oil" chain is bad, because grime sticks to it, lube is wasted, the chain "irradiates" dirty oil around (over the bike, trousers, socks, etc.).
I am also aware there could be a "magical point" where the chain is already lubed but not soaked yet, and that perhaps happens when you don't put so much oil, so as when you "run" a thin string of oil over the slowly spinning chain, instead of dripping a (whole) drop of lube in every roller.
Finally, I'm aware too that oil outside the chain is pretty much useless, and the only part that MUST be lubed is unfortunately harder to reach - the inner surface of the inner-plate holes, where it spins around the chain pins.
So, the question is: "Is there anything really bad that happens to the drivetrain if you don't wipe excess lube immediately, or is it just a practical measure to make life easier (or something else)?"

A:

The excess oil collects grit from the road, which acts as an abrasive that will wear out the chain.

A:

It's the oil on the outside that collects dirt.  I generally over-oil the chain fairly substantially, using a slow drizzle as I crank the chain through several times, then wipe it well.  Wait a few minutes for some oil to ooze out and wipe again.
Others like to drip a single drop of oil on each link and do a little tap dance after every third link.  Whatever floats your boat.

A:

Another possible effect of over oiling without wiping the excess from the chain is the chain slinging oil onto the brake surface of the wheel.While this has no effect on the drive train it does effect brake performance.

