Marriage is of course one of the central themes of Austen's classic novel, and comparing marriage today with how important and essential it was in her day does give the reader greater understanding of the characters and their motives. This is of course very apparent in the case of Mrs. Bennet, whose desperate attempts to marry her daughters off make her ludicrous to the 21st century reader, but when it is remembered that her future and that of her daughters is very insecure until she succeeds in one of her daughters making a good match, it can be understood more clearly. In the same way, another issue that perplexes 21st century readers is Charlotte's accepting of Mr. Collins, who is clearly the most ridiculous of individuals. However, note what Austen reveals about her motives:
Without thinking highly either of men or matrimony, marriage had always been her object; it was the only provision for well-educated young women of small fortune, and however uncertain of giving happiness, must be their pleasantest preservative from want.
Marriage then for a plain-faced 27 year old was the only escape from spinsterdom and being dependent on others for the rest of your life. Marriage was therefore a much more serious and essential part of society for some characters. In today's world people have the option to marry or not to marry. In Austen's time, for some people marriage was a matter of survival.