Increasing the team number doesn't affect the quality of the tournament in any means, only the tournament schedule gets extended. Among the entire sports league played around IPL is among the top 10. This has come as a result of perfect organising. In between some issues arise and two teams weren't allowed to play the IPL. If it is a drama this could've never been this successful.
One suggestion would be to increase the threshold for the number of overseas players in the playing XI from 4 to 5. I have a suggestion that we don't have 70-80 quality players in India who can be evenly distributed to all the 10 franchises. And we saw this during the last IPL, when the Sunrisers Hyderabad struggled with their local contingent. Last year there were only 8 franchises. From 2022 onward, there will be 10. So I guess the shortage of local players will be felt more. The increase in overseas players can neutralize this.