Should wedding guests be responsible for helping to pay for the big day?

One bride's message that is making its way around the internet seems to suggest that.

In an article on the Huffington Post, a viewer shares a message she got after attending a friend's wedding.

The viewer, Tanya, said she and her boyfriend gave the couple $100 as a gift. Tanya said she felt that amount was appropriate given her financial constraints -- she just graduated with $40,000 in student loans and is working part time.

However, the bride had a different feeling.

"Hi Tanya, how are you? I just want to know is there any reason or dissatisfaction of Mike's and I wedding that both you and Phil gave 50$ each? In terms of the amount we got from you both was very unexpected as a result we were very much short on paying off the reception because just for the cocktail + reception alone the plate per person is 200$ (as per a normal wedding range with open bar is about) and Mike and I both have already paid for everything else including decor, photography, attire etc and didn't expect we had to cover that huge amount for reception as well. As I know you both live together and work, so I did not see any reason for that amount, when it comes to your wedding hopefully you'll know what I mean. I hope for the best as from what we receive is what we will give back. Anyways, good luck on everything." [all sic]

What do you think? Is it OK for the bride to express her thoughts? Should guests assume that by attending they should give money to help pay for the reception?