Decoration, but in general they are really not that important. I like ours because I got it for $40 new on ebay when it usually costs $200, but I wouldn't really spend a lot on it and think the emphasis on how "girly" or "boyish" they are is kind of silly.
Ours may be considered girly, but if this baby is a boy, too bad, he's going to use the stuff we have.
The point is to play on your tendency to coo over cute things and try to sell you on things you don't need and charge you an arm and a leg for it.
The baby industry banks on the fact that you are emotional and excited for baby...so they make sets that are unneeded, poor quality and over priced.
There is no need for anything but the sheets. The rest is pure deocrational.
A kiss he will never forget- Disney World 2014
To make Mama happy
Eh, well, we use a bumper & skirt too, so YOU may not want anything but a sheet, but we do. We used a bumper with DD (gasp!) and it helped a lot, and the skirt helps hide the ugly black coils the mattress sits on. Also, DD is now using a comforter, so it DOES get used eventually.
FWIW, I would never spend hundreds of dollars though. We got DS's for $50. I couldn't buy separates for that.
I was wondering this, too, so thanks for the answers everyone.
I got 6 cotton-knit fitted crib sheets at Ikea this weekend--four in white and two in green. Cost about $15 and I'm all set as far as bedding. I can throw some stuffed animals or blankets in there if I want to up the cute factor, otherwise, not bothering. I'd rather spend money on baby clothes or books or something the baby will actually need/use at some point.