You know what is the reason of suddenly decrease of lot size what SEBI was rejecting every time.
It's the recent effect of newly increased margin thorough ASM.
There was discussion on CNBC that the recent fall in many NSE Stock Future is bcoz of suddenly liquidity crisis due to various recent restrictions. And bank nifty was facing some wide bid-ask due to increase of ASM too.
It's SEBI effect.
Tried to cut retailers participation by increasing margin, as a failed effect needed to decrease lot size suddenly, now retailer will easily participate with half lot size now.
All the possible effect of bad liquidity due to such various restriction was discussed in SEBI thread but no one is listen to them from higher authority and suddenly they are feeling the heat.
Now small traders will trade bank nifty more peacefully. And bank nifty options will get higher liquidity.