Why would anyone want 180g records ?

Put simply, vinyl weight promises nothing but extra grams of PVC.

Mr. Sayles, I couldn´t agree more.

When I got back into vinyl in about 2005, after a 20 year hiatus, I was initially very impressed with the heavier vinyl pressings.  But after a few years of purchasing many mint used records of all thicknesses, I heard no correlation between thickness and sonic quality.  I think they press heavier now because they believe the marketplace demands it and to give what audiophile customers will perceive as a premium product.  

Lighter weight pressings are more likely to warp over time. Whats not talked to here is scratch resistance. The old RCA's and Columbia pressings were pretty tough... you could scratch them but it was rarely more than superficial with minor "tick" sound. Later pressings were much more easily scratched with the resultant  deeper scratch "pop" sound that would make it hard to enjoy the album.

I never put a scratch on a record. Just don't play the table when you drink and you'll be fine.