Trademarks are different from other immaterial monopoly rights that
government grants, because of their ultimate purpose is to prevent fraud,
not to prevent others from using an idea. Committing a fraud is to give
another person false information so that they would act in a way harmful
to their interests. By preventing me from selling jeans and claiming them
to be made by Levis, government does something good - it makes it less
profitable to harm people by leading them to bad actions. I should,
however, be allowed to make jeans that look alike, use the same sewing
techniques and same materials. But I should not falsely be entitled to
claim that they are made by Levis.
Thus, the trademark legislation may need change, but it should not be
completely abolished. The main purpose of government is to protect people
living on its lands from violence, theft, and fraud. This mission comes
from the fact that government holds monopoly over use of violence in its
territory and only that makes it possible to protect people from violence,
theft, and fraud. Government also takes on other duties, but none of them
can be considered as essential as those above, because at least in theory
it is possible for others to handle those duties. You may argue that not
in practice, but that is not relevant to what I say here, because the ones
impossible even in theory do take precedence over those that are possible
in theory (and maybe even in practice).
Thus, it is the duty of a government to create a society, which can reward
those who serve others well and punish those who would harm others.