Why would anyone want 180g records ?

Raul, that's a great point about record prices going up, not down.

I think record prices will remain high due to record pressing plants having to maintain and upgrade equipment that has been put back into service, plus there are a number of new record plants with start-up costs.

There may also be a greed factor; record labels and vendors wanting to make quick money while the vinyl business is hot.
A typical price for a 180g LP at SS Direct, Music Direct and others used to be $24.99, now new releases are higher.

Highest quality vinyl I have is Japanese from seventies and it's not 180g. I think, these thick and heavy records are a complete waist of the resources, you also have to adjust the tonearm each time you play them. In addition, I tried couple of 180g reissues, and I don't know whether it was remastering or the weight and thickness of the records or both, but I didn't really like what I heard, it felt kind of 'stupid'. Maybe my Spacedeck just doesn't like them, yeah maybe, I am quite certain it was not voiced and tuned using them. Anyway, just give me older Japanese quality regular weight vinyl and I'll be happy.

"Elephant Mountain" by the Youngbloods came in 3 different thicknesses over the years.  The thickest(and probably the first) one sounds substantially better than the other 2, but maybe it was due to other factors.  I've also not found copies of the thickest nowadays.

I have an audio mag from the 70's at home (Stereo Review, IIRC) with a short piece covering a record company's hyping of its new thinner pressings.  The claim was the thinner vinyl would sound better.  Now records come with stickers hyping their increased weight.  I seriously doubt if the thickness of the record has any effect on sound quality.

I've read from a few sources that 180g has better longevity because, naturally, a record is worn down over time from the fact that the sound is produced by scratching a needle against it. More material translating to longer play time without diminishing sound quality.

Of course, I have no idea if that has any validity to it. And even if it did, you'd probably have to play the record constantly for about 100 years. But it's interesting, nonetheless. :-)