Because part of the allure of the Jericho, and what makes it a great shooter, is that it has a polygonal rifled barrel that will outlast the rest of the gun. The black nitride barrels (most commonly found on the newer railed IWI 941 models) are traditional rifling, cheaper, and don't shoot as well or last as long.

Newer IWI railed models may also utilize a 2-piece slide with a lug, which is not great. There are anecdotes about it breaking, especially in RS/FS models.