Hide Pants are a craftable middle-tier leg-covering armor piece in RUST and are available to all players as a default blueprint. The current iteration can be traced back to the implementation of Leather as a component as early as August 2015.
The most commonly associated item set when used in comparison for the hide armor set is burlap, requiring roughly the same amount of Cloth as hide requires Leather. In the case of the leg armor slot, it actually takes more cloth to craft the Burlap Trousers as it would leather to craft the hide pants. In the apples, to oranges, defensive statistical comparison, hide pants have considerably higher bite protection but notably lower cold resistance than burlap trousers.
While in an ideal world there are plenty of resources for all, but on a small map during a fresh wipe day, you make gear from what is available. Cloth, in the beginning, can be a rare resource, and being able to fashion gear from leather instead might just leave you with enough materials to craft things like sleeping bags.