There's a military reason why and you're apparently missing the obviously!
Let me please spell it out for you. Iran needs less and less missiles to inflict sever pain on the occupying entity. Why send missiles in the hundreds when much less will suffice? Interception rates have drastically gone down. The combined forces of zionism are not even able to down the a few missiles anymore.
Don't worry. It'll soon by time for the drone face once AD shield is weakened enough. All this is calculated. If Iran wants to send in hundreds of missiles as a show force it can easily do so but thank God for the cool heads and calm minds running the show in Iran!