Islam, as an all-embracing religion that deals with all aspects of life, lays down rules and regulations that set the affairs of people in order and spread peace, welfare, prosperity, and well-being.
In the field of clothes, for example, Islam commands Muslim men and women to abide by certain code of ethics. Muslim women’s dress (hijab) serves as a good example in this regard. Men, likewise, are forbidden from wearing gold and silk.
As regards your question, we’d like to cite the following fatwa issued by Sheikh M. S. Al-Munajjid, a prominent Saudi Islamic lecturer and author:
“It should be known that Allah, Most High, is Wise in His commands and prohibitions. He does not command anything except that which is in people’s best interests and He does not forbid anything except that which is harmful. People may or may not come to understand the reasons behind these commands and prohibitions, although Allah has His Wisdom in any given issue.

Having said that, it is still not right to make following a command or prohibition dependent upon knowing the wisdom behind it; rather we should hasten to carry out the commands of Shari`ah, regardless of whether the wisdom behind it is clear to us or not. If it is clear, then praise be to Allah, and if it is not, then the Muslim should not let the fact that he does not know it prevent him from acting in accordance with the ruling of Shari`ah. This is true submission to the command of Allah, and Islam means submission to Allah and obeying Him.

If a person makes his actions dependent on understanding matters which may or may not convince him, he is in effect following his own thoughts and desires, not his Lord and Master.

By no means does the above mean that it is not important to look for the wisdom behind the rules of Shari`ah, or that doing so is forbidden, but we should not make knowing the reasons a condition for acting upon the ruling.
As for the point in question, the scholars have discussed the reasons for silk being forbidden for men. For example, ibn Al-Qayyim suggested in his brilliant work, Provision of the Hereafter, that:

“Among those who believe that there is reason and wisdom (behind the rulings of Islam) – and they are the majority – are some who answer that Islam has forbidden silk so that people will keep away from it for the sake of Allah, so they will be rewarded for that. Others reply that it’s basically created for women, as is the case with gold jewelry, so it’s forbidden for men lest it corrupts them by making them resemble women. Some scholars maintain that silk is forbidden because of what it may lead to in the way of pride and showing-off. Others relate the ruling (prohibition) to its having effect of femininity on men, as it goes against his masculinity and manliness. This applies to all men, even the most masculine and chivalrous of them. Whoever is too dense to understand this should just submit to the Wise Law-maker.” (Provision of the Hereafter, 4/80)”.