The real test is in the marketplace. If a font is inferior, it will not succeed. Any time this is claimed as an individual accomplishment of a solitary type designer, it is immoral, plagarism and no more than thievery. Even the formal inclusion of the already existing lower case characters which had evolved was a choice based on things that were already accepted in the culture of the day. Wood Types are more of the same - copying from wood blocks.
Many type designers knock off designs from contemporary competitors.
This only differs in the fact that these people, unlike the copperplate engravers, Petrarch, Scribes, or Roman monument makers, were in business to make money from the same form of type. In the early 1980s, Linotype was unwilling to license their designs to Bitstream. Historically speaking, I don't believe any money changed hands. Legally speaking, they were in the clear - as they would have been if they merely extracted the outlines digitally. Morally speaking, they seem to be standing on the common-law principles that have arisen in the industry over hundreds of years.