Why? It's just a place where you can buy music, and store it on your iPhone and iPod, so you can listen to it anywhere. Where in that means you shouldn't support iTunes?
it's also a place that forces artists to use their file format, charge their high prices, takes a VERY good chunk of the artist's profits, doesn't offer higher quality options, and doesn't let artists offer bonuses with the album apart from songs
sell the itunes gift card and buy some albums from bandcamp instead