Off the top of my head I can think of a few reasons I like to (or have to) use Projects:
Individual application instances (avoiding collisions)
Working on targets e.g. Real Time and FPGA - I don't think there is any way around that
You need to deploy Shared Variables from a Project, you can't do it just from the Library
Creating Libraries/Classes/X-Controls
Configuring Inheritance
So I am the opposite, I rarely don't use them (by choice or otherwise)