So many reasons! If you can change your mindset about how much luggage you need, you can travel stress free and for longer than you could ever have imagined.
Change this for this
Economy - can use budget airlines with cabin luggage only, can take cheap local transport and no porters to tip!
Security - easy to know where your possessions are as you have your "whole world" with you at all times
Flexibility - Catching buses, trains and ferries are so easy, as is walking to find accommodation
Beat the Queue - First in line for immigration and customs
Options Enhanced - where you stay, what transport you take is easy when you can swing your luggage onto your back
Change your mindset about luggage!