Because time is of the essence, they need to destroy the DS as soon as possible. They can't just go anywhere else, that just puts whatever planet they are on in danger.

It is suggested that it would be too dangerous to delay and allow DSI to be at large.

However, it is ludicrous that you would lead the DS directly to your secret, main base of operations. Leia was willing to risk Alderaan to hide Yavin's location. Then led the Empire straight there.

The Falcon was much faster than the DS so they could have handed the plans on to another operative. Then led the DS on a merry dance across the galaxy whilst the plans were analysed.

They would have had time to draw up a considered plan to assault the DS at their choice of destination.

But plot convenience required the tense, will they, won't they, finale and the stupid decision was allowed to stand.

Were I a Rebellion leader and one of my operatives did what Leia did, I would be looking at a court martial to discourage anyone else doing anything so reckless and idiotic.