In no particular order: -
Probably due to the fact there's a S/C version of the engine in the family making most of the parts required for the conversion available off the shelf.
S/C in general is often preferred over Turbo because of the more linear power delivery.
It's difficult / expensive to get more N/A power making S/C instant BHP / torque gains attractive.
Maybe people with M62's like their cars to sound like demented domestic appliances? (Not a fan of the noise - can you tell? 😃 )