What is the reasoning for preferring clients with high data rates? I've stumbled upon this just a handful of times and can't firmly grasp the concept.

Per Aerohive Doc - Explains their implementation,

rate-preference-weight | Set a preference for forwarding traffic to and from wireless clients that are capable of fast data transfer rates. (Default: high) none Set no preference for clients with a fast data rate moderate Set a moderate preference for clients with a fast data rate high Set a high preference for clients with a fast data rate 

So let me ask /r/networking, what is the reasoning for preferring clients with high data rates? I can see both sides - What is the general rule of thumb in design?

Cheers! edit: Format.