Question

. The spleen is often surgically removed after even minor damage. Why? What function, if any, does the spleen perform

Answer 1

OOOh, the spleen is cool!

It has white pulp and red pulp, with different functions. It's a filter, removing old, damaged, or imperfect blood cells from circulation. It also stores (in reserve) immune cells and red blood cells for occasions when they're needed rapidly (within minutes - longer term, the body can make more in bone marrow, but release and maturation will take hours to weeks).

Answer 2

Additional information semi-ontopic:
You'll be much more likely to develop a lunginfection if you've had your spleen removed,
It won't be a big problem but you will have some old erythrocytes in your circulation which the spleen would have normally taken care of.