Why does Antique Furniture value more ?

Question

Age/Design/Authenticity/Color/Passion

Answer 1

All of what you mentioned.  Plus, often it was simply better made and made with materials which are either no longer available or no longer able to be used.  Who made or crafted the furniture also plays a part.  Sometimes it is because they became more well known and famous so their pieces became more desirable during their career.  Sometimes it is because they were know to produce unique, high quality pieces from the start of their careers in making furniture. And sometimes it is purely historical significance in that a particular piece is representative of what was happening during the time it was made.

Answer 2

Supply and demand. Plus the quality of the craftsmanship is usually very high.