Well it certainly isn’t for the cricket ! It’s everything business would want
Short (perfect for tv, attendances)
Ideal for the drunk louts (there are enough at 2020 so I suspect more will attend this format)
Sponsorships for all the different aspects like the IPl/big bash
Maybe I am wrong, but it strikes me as something someone without any commercial awareness would come up with in the assumption that it was want business would want. The IPL is a massive success in terms of the quality of the cricket, the size of the crowds and the commercial revenue it generates. The franchise system put the teams in the hands of people with business backgrounds, not existing clubs with cricket backgrounds and strangely there was no attempt to reinvent the wheel with the format.
Really, I think the ECB has run with the 100 format as fudge to protect the vested interests of the counties by allowing them to continue with the T20 Blast which already attracts less star players than the Caribbean PL and will surely only diminish in quality further. If this was a purely commercial decision, you would abandon the Blast and adopt the City based model which seems to be doing rather well for itself in other countries as far as I can see