All it does is give an element of risk when you try to use the supp to gang. 20% chance of backfire if you have one person with you when summoning is not a lot. 40% for a trio is not a lot. Even with 4 people waiting to gank the one it is only 60% chance of backfiring. It still has tactical uses. For example, if you use it during a raid you can get yourself inside the enemy cabal to cause a bit of chaos whilst your allies kill the outer.

I'm not trying to make all fights one on one. I'm trying to remove "risk free" gankings. Summoning to a large group is one of these tactics (because if you have many allies in the area, then even if you fail it won't matter much). By sending you the other way in that situation it simply forces those who try to use it to gank to fight alone now and then. Those who can handle that shouldn't have a problem.

The change to nightgaunts, allowing you to get carried off uninjured, was a similar change. It allowed you to put the conjurer at some risk.