Because certain trends burn out. Take the Crypto and NFT trend, where for over two years developers were trying very hard to convince players that somehow NFTs in games were a great idea. Last year they they had backpedaled on them to the point that it's no longer talked about. The only adoption was via the industry, and even then they were facing an uphill battle for their use.
AI seems to be facing better adoption, but it remains to be seen wether it will have staying power. Tech comes and goes all the time.
Gacha games are gambling and I hate gambling but they seem to have taken off in the west. But it's the slick marketing aimed at mens penis that annoys me. Why all the scantily clad anime girls guys why? I was hoping that as a trend would die off but it hasn't