IMHO, if you plan to leave the engine stock or nearly so, and you have no signs of crank issues like pinion shaft runout, I can't see any compelling reason to tear the entire engine down to do this. However, if you plan to have the engine apart anyway, especially if you're boosting performance, it would be highly recommended. If you're going to spend several grand on performance engine work, why take the risk of having to tear it all down and do it over because the cheap stock crank couldn't handle the extra torque? Kind of like the old Fram commercials, you can pay now, or pay a lot more later.
Like a whole lot of services and products offered for Harley's, it has it's place under certain circumstances, but it's not necessarily beneficial for anyone and everyone.
Jerry