Me too, and have done it in the past on one laptop that I did get with Linux when there was no bring-your-own option, but I suppose that OP's got a point --- there are people out there for whom installing the OS on a blank laptop is going to be intimidating.
If you've installed an OS a zillion times, this is all old hat. If you never have before, probably feels kind of scary.
For those people, having a preinstalled OS can be a significant value-add.