I agree that letter casing is nice from an aesthetics point of view, but there can be exceptions when characters can be confused for another such as the letter i and the letter L.. what do you do when you have a domain called AllIdeal.whatever. Have to get creative.
Like many nuances in domain names, case by case basis.
On the example from the OP post, actually I think the all-lowercase is the nicest. Single-character upper-casing in a phrase domain can be touchy because it's followed immediately by another uppercase, thus back-to-back capital letters. Yuck.