Saves them the hassle of doing all the paperwork for H1B and later GC if they want to. And also, they can let that employee go when the project is over. Doesn't have to pay for the airfare back. That's when the employee "sits on the bench" till he is assigned to another company for another project. L1 is now widely abused and many say it is used as a substitute to H1B. Plus it has it added perks - they have no wage determination and the spouses can work immediately. USCIS is well aware of the L1 abuse. Yet they still needed a Presidential memo to clarify this mess. And this too has no timeline just like all the other stuff for the legals because you have to follow the "regulatory process".