Because you want a Wheaton x lurcher to catch stuff and kill single handed, regardless if it's getting stick
The best ones i have seen were full on, when the red mist comes down - that's what you expect in a Wheaton x lurcher.
I'd want a busher to be steady and thorough, not missing bits of cover because it's like a bull at a gate. Nose, feet, coat & ability you can get from a number of other breeds more suitable temperament wise.