Ideally, the revenue should be divided equally between these 16 countries, with another share going to those teams which failed to quality. But the BCCI want half of the revenue from the world cup. Is this fair?
I wouldn't call that ideal. To be fair, it all comes down to which country contributes the most towards the revenue share and we all know that India leads that list. It's simple really. The more you contribute, the higher the revenue share.
The other boards are already agreeing to a lot of unjust demands made by the BCCI. They allow their players to participate in the IPL, while the BCCI never allows the Indian players to participate in the other leagues. No major tournaments are conducted during the two-month IPL window, while none of the other leagues, such as BBL and CPL enjoy such largesse.
Truthfully speaking, IPL is another league when compared to the tournaments that you mentioned in terms of popularity etc which is why they are in the position to make such demands.