If you actually believe that there's not much I can say... If someone shoved that much money into your pockets I'm sure that you could find an excuse easily. "Developing the game" is the easiest and most overused.
David Beckham doesn't care about the MLS quality, just as Zee don't care about Indian Cricket quality. They care about getting money and beating the BCCI.
National pride for your own domestic scene would be tarnished if people start moving to India to make some money instead of playing at home for the team that they trained and grew up in.
David Beckham is many things, one of them isn't caring about Football. He is a footballer through and through. Sure he's being paid a bundle, but a fair chunk of that is going back into the game through his outstanding academies.
This ICL thing, is something which people will watch because of the names. But it's not going to be a place from what we say "Player X played really well in that league", because it's not going to be a place where people ge the chance in the Indian team because the BCCi have said so and also because it's going to be dominated by thirty somethings.