According to Wikipedia, "a generic drug" is a pharmaceutical drug that is equivalent to a brand-name product in dosage, strength, route of administration, quality, performance, and intended use. In many cases, the drug manufactured and sold after patent has expired is referred to as "a generic drug".
Like a generic drug, in many cases, furniture manufactured after design rights owned by a famous designer has expired is referred as "generic furniture".
Although design is identical or similar to the original one, "generic furniture" is sold at a low price.
The image below is one of furniture design registered to Japan Patent Office. (design registration no. 1477213)
Motomi Kawakami, who is a famous designer is "the creator" of the above mentioned design rights.
In this way, furniture created by famous designers is also protected by design rights. However, after the design rights expire, similar design furniture might be sold as "generic furniture".