One meaning of Dharma is 'duty'. It is what calls upon us, what leads us to do what may not be easiest, most convenient, or most pleasurable, but which is most important.
A life well lived requires sacrifice, something which causes you to overcome your own selfish impulses and serve the greater good. Dharma is that principle. Without such a principle, how can you guide your actions? Dharma is like the thread on which all of the moments of your life are suspended, to create a coherent shape.
People may be cynical about religion, but what principle will they replace it with, if they get rid of it? Certainly one's inherited drives do not often carry you towards the best of all possible outcomes. Why bother doing good, or being good, if there is no good?
I think this is why the teaching about Dharma always calls for a lot of effort. Left to one's own wishes and devices, one is likely to pursue pleasure and comfort, rather than what is most needed. Simple fact, but important.