It would allow people who come to this country to get into work faster, and allow UK citizens to build savings more (or spend more on luxury goods, if so inclined) thus increasing the integration into society and stimulating the economy.
I would like applicants that come from outside the EU in order to marry a UK citizen to be able to work as soon as they arrive in the country. By denying them both benefits AND the right to work, you act to ensure that only relatively wealthy people can afford to come here, and you also ensure that people with savings are forced to use those savings to support living costs!
My now-husband would have been very happy to have worked as a cleaner or similar in the first three months in order to contribute towards the household expenses. As it was, he ended up having to rely on me to provide for everything, which does not foster a sense of equality and partnership in the marriage.