Does this not also create a single point of data for thieves wanting to know where the best bikes can be found? One tiny data breach, or one disgruntled employee, and all those address/bike combinations are on the dark web?

The address optional. So no its not required to provide your address.

Also that's not a non zero chance there are people like this but honestly, whos gonna get on a plane in today's economy, fly to some random place, break in to someone ones house all over a what is on average a $2k bike. IDK risk vs reward seems a little crazy to me.