Also as fans we wanted more T20 so what was ICC going to do ignore the fans voices?, and now when we have more T20 we blame ICC for not doing enough not sure who’s to be blamed the fans or ICC?.
IPL benefits only a few boards such as WICB, CA, ECB and CNZ (because the IPL pays 20% of the player's salary as foreigner release fee). Smaller boards as well as the PCB don't benefit, as they don't have anyone from their country playing in the IPL. And I don't know whether the ICC receives anything from the IPL revenues (my guess is that they don't).
Now coming to T20, I agree that this is the most popular format as of now. But the ICC is still headed by traditionalists and for them the test cricket is first priority. Take the case with any full member. On average, the national teams spend 50-60 days each playing test cricket every year. For ODI, this waters down to 20-30 days, and for T20I, the number is even lower.