Difference of material comes to play
Leather is many more times durable than textile materials in testing. However, it is far more susceptible to water and weather. Like any other leather, if you let a jacket get wet, it will degrade from that point. Moisture like sweat will also damage leather. In the worst case, it might mold, both making the jacket stinky and compromised as a protective layer.
Textiles, being synthetic fibers for the large part - are immune to moisture. Sweat will make the jacket stinky all the same, but won't make it mold and fall apart. It also handles weather well, and can be made to be water proof. However, the ability for the jacket to protect you is lower than leather. The other thing is the vulnerability of synthetic fibers to UV radiation degradation. Nylon, and especially Kevlar breaks down in sunlight. it is said that a bulletproof Kevlar vest retains only 20% of its initial protective capability after 3 years of wear by police officers. Leather, if kept oiled and cared will not suffer from this same degradation.
When placed into the context of a every day-rider. Textiles tend to be more comfortable over a range of temperatures. They also require very little special care, such as special leather soaps or oils. They protect well, but not as well as full leather.
Full leather offers the ultimate in rider protection, but require a significant investment in maintenance work. But the payoff of a leather jacket is significant. Unlike textiles, leather will stretch and form itself to its wearer after some time. After this break in, well aged and cared for leather looks undeniably cool, and something that can't be imitated.
also: nice nick
