I think it definitely depends on the wedding.

My brother recently got married and DH didn't wear a tie. It was a small wedding and we knew it wasn't a fully formal affair. In fact, the groom and groomsmen didn't even wear ties. They had that spunky beach wedding look where they had the top button of the shirts undone. The wedding was on a pier which really suited the look (although the weather didn't agree and it was blowing an arctic gale, lol!). Their reception was a stand-up ****tail type reception.

We are going to a wedding this afternoon though that is more formal. It is a church wedding and then a formal sit-down meal reception, so DH will be wearing a tie. In fact, he just had to go out and buy a new shirt because he found a "spot" on the one he was going to wear, hehe.