Why do you think the Laputians only concern themselves with Mathematics and Music?

Music:

"...my tutor informed me. He said that, the people of their island had their ears adapted to hear "the music of the spheres, which always played at certain periods, and the court was now prepared to bear their part, in whatever instrument they most excelled."

"I have not seen a more clumsy, awkward, and unhandy people, nor so slow and perplexed in their conceptions upon all other subjects, except those of mathematics and music. They are very bad reasoners, and vehemently given to opposition, unless when they happen to be of the right opinion, which is seldom their case. Imagination, fancy, and invention, they are wholly strangers to, nor have any words in their language, by which those ideas can be expressed; the whole compass of their thoughts and mind being shut up within the two forementioned sciences."

As you can see from the above quotes, the Laputians are unable to reason or imagine. Everything is black and white, hot or cold. Thus, they embrace the rote, exact sciences of mathematics and music because they are based on precise action. They couldn't think outside of the box, so they stayed inside of it.

math because they all are great mathematicians and so thats why they made large house and many other things that help him