I remember, the reason was people don't wanna spend whole lot of time for just one game.
That's why playing Inter bo3 makes its standard points more. (50 instead of 40)
Now if the opponent don't want to play bo3. I guess it is ok for the Inter player, cause he can play more Inter in the time we could be playing other 2 games of that bo3.
In other words, He supposed to earn 50 points by playing bo3. Now for example he gains 30 points for inter as bo1, but he has time to play another league game, maybe another inter bo1, and gain 30 points again. It will be 60
Not sure about that 30 yet though.