Question about leather?!

Question about leather?

While I understand that leather is an animal by-product, death (& possibly cruelty) is involved in its production...
How is it better for the environment than synthetics?
Synthetics don't last as long thus get replaced more often, are not a natural product, non-biodegradable & in the long run really bad for every living thing...
I'm honestly pondering the logic behind not using leather. I know leather takes 20-40 years to biodegrade, sythetics take at least 450 years... Perharps this post will be more suited in the environment section, but I would like a vegan take on this.

Please be nice, this is an honest question. Thanks :-)

2 days ago
The pollution argument doesn’t hold.
Pollution in production of leather is negligible compared to pollution created in the production of synthetics.
Significant amounts of fossil energy carriers are used for the production of synthetic organic materials; this does not include production waste & disposed matter that has to be combusted.
Waste that requires combustion is mainly composed of plastics, synthetic rubber, synthetic fibers and carbon black.
The U.S. Environmental Protection Agency (EPA) estimates that non-biogenic materials in combusted waste produced emissions of 19.4 MMT carbon dioxide in 2004. Carbon dioxide emissions represent about 84 percent of total U.S. greenhouse gas emissions.

2 days ago
Be FRANK, are you're being lazy and trying to sneak in 2 points? :-P You can play.

If I had to make a choice between leather and synthetics, then yes, I think my environmental stance and my vegan stance would be at odds.

But I have to admit, I can't think of a time I've had to make this choice in real life. T-shirts are cotton, my sneakers are part canvas and part rubber, my bicycle seat is the same synthetic type that comes on all the bicycles. I -never- have a choice between leather or synthetics, so I would be buying the exact same things whether I was vegan or not. Am I missing something here?
Edit: I get that you're talking about sustainability, but I think the question presents a false dichotomy. We don't have to choose between, say, a real leather couch and a synthetic leather couch, when we have the option of one of those fluffy cloth couches. Or in some homes/cultures/countries/etc., no couch at all. I think over-consuming is more of a problem than leather vs. pleather.