Wedding invitations communicate love, celebration, commitment, plans, dates and locations; they're just full of information. The style of the invitation reveals the personality of the couple (or at least the bride?), as do the ceremony and reception locations. They are providing us with a little preview of what to expect on the wedding day. Some invitations suggest romance, while others are more modern; invitations can be energetic and colorful or strictly traditional.
I consider it an honor to receive a wedding invitation because the exchange of vows is personal and intimate.