Short answer is : For your own good.
Technology has made dreams of an ancient-man come true. You can video-talk to someone sitting thousands of miles away, can travel at a speed unimaginable a few hundred years ago.
Despite having these external facilities today, man may feel discontent with life. Or a man may not live life to one's fullest potential.
The rishis knew truth that the human nature will not change. We will always have tendencies of selfishness, competitiveness and fairness/justice and more; like anger, jealousy etc. They understood that *beyond a point* the externals will never satisfy us.
Let's take one aspect of human nature, fairness. If only you have the ability to travel instantly to distant places; it will certainly make you feel more content. However, if everyone has the ability to travel in an instant, it won't make us feel more content. As is the case with most external technologies. The external advancement is insufficient for a fulfilling life.
Therefore, it is foolishness; to deny the need of a system; that regulates the internal.
The rishis emphasized on the internal. With the knowledge of the internal truths, one can enhance the experience. The religion and the scriptures deal with this aspect.
Listen to the rishis for your own good.
*End