When was the last time a player from one of the associate nations got a chance to play the IPL? I guess Sandeep Lamichhane of Nepal got a couple of outings and after that he was dropped. IPL franchises prefer players from SENA nations - Australia, New Zealand, South Africa, England and also from West Indies. Anyone outside this grouping doesn't stand a good chance to get selected. Now coming to the tri-nation series, these two teams (Nepal and Malaysia) are the ones with native players. But in recent times, they have gone down in ICC ranking, as they are unable to compete against mercenary teams like the UAE and Oman.
I think IPL is always going to prefer the players who bring much more attention and also so can play surprising and big innings when they are needed to do so.
In my opinion, the players from these associate nations are not the type of players who bring attention or the skill that is needed. They did experiment with Sandeep Lamichhane but that didn't work out as expected in my opinion.
Obviously, there is another fact that if the Indian players play with the better players they will learn a lot more instead of playing with players or against players from these associate Nations.