Increased liquidity. Also option trading is usually in 100 share units, meaning retail investors can now afford more options (e.g. $15,000 vs $300,000 a unit).
Anecdote warning:
This is one reason I have not been able to buy/sell google options. (I did around Brexit when google was 650 or so, but not since). Even a single contract is a massive risk for a layman portfolio like mine. 1/20 will imply I will definitely attempt to trade this.
