I agree that i often prefer to reduce definition, but that doesnt mean definition at 10 always sounds bad.
Definition is similar to pre-eq'ing the signal before distortion. CK has said that. Higher definition settings are likely to be found on rigs with a screamer or similar "tightening" boost.
I agree i usually would prefer non boosted profiles, but there are lots of counter examples. For instance, Premier Profiles uses an OD820 on many of their profiles and they sound really really good. The way they set it up, the Definition isnt maxed out, or even if it is, the tone isnt too thin and shrill. Tim Owens HAWP BE-100 profiles feature no boost pedal, but some profiles came out with Def on 10, but they arent harsh sounding.
I would also agree a maxed out Def setting must be limiting the range of what tones can be profiled. Ive requested it be expanded in the past