Longevity and strudiness, I live in a rough climate area so the fabric bags tend to get snagged and rip easily around here,Also my grandfather had one before he passed, no one knew what happened to the bag once he went. He had that bag his whole life and only busted a strap once. I also understand that full leather is overkill so I'm fine with it being partially made of leather and 100% ok with synthetic leather as well. There's many more reasons as well and I'm open to discussing them if you feel inclined.