Along with other factors, customizability is always dependent on the medium.And it can be both a boon (when you don't have something very specific in mind and are positively surprised by the other person's creative input) or a bane (when you had something very specific and wanted a "perfect realization", but gave up because well, you can't really ask for an unending string of minor modifications to be included in the price of the commissionned work). There is certainly a place for both methods.
It was less about the attractiveness of the first sculpture- though that is always noted- because Guillame’s version is still clearly a beautiful male figure. But he also more clearly emphasized that this wasn’t just any Angel, but Lucifer the Fallen himself by his use of traditional iconography, such as the chained ankle and the small (but visible) horns of the second statue.This was especially true with statue. In your example, the commissioner failed to mention that Lucifer shouldn't be too handsome, and the artist focused on the "angel" part of the fallen angel, but it's more expensive to change a statue than touch up a painting or edit a digital art.