Some nobles are bad, some nobles are good. I once had a tax collector that liked adamantium - I named him Goblin Bait, and he became my first line of defense against the green menace. That or I stuck him pulling an utterly pointless lever in front of the fortress and then built fortifications around him. It's still debated as to exactly what role he played.
On the other hand, my Baron (now duke) really loved brass. His tomb holds a brass sarcophagus in a chamber that has been platedd, wall and floor, by brass. A few times every year he will mandate some more brass bars (or blocks, or statues, et cetera) be made. He has a nice garden filled with brass statues.
His wife loves spears. However, most of these spears are currently upright and attached to gears, as she also likes blue diamonds. Just in case. She hasn't said anything yet, but I'd like to think that if she does ever ask for a blue diamond something, she will at least die happy.
My tax collector likes silver and goblets. Naturally, his room now holds several chests filled with silver goblets.
It can be fun to spoil your nobles just to add flavor to your fortress. Imagining future adventurers cracking open a door and stepping into an ancient tomb covered top to bottom in brass, or finding the remains of a dwarf sealed within an improvised gibbet at the front of the fortress.