I understand a lot in your game is based on "RNG", but when some of your players decide to spend their 1400+ splinters and get 6 dupes out of random hero boxes with a roster of 30 heroes (27 left to unlock), you have a very high chance to lose those players. So, this is a lose lose scenario and I do hope your team thinks things through and focus your game less on RNG and more on rewarding players who are part of it who put their time and effort to enjoy your product.
I have alternatives and for me Marvel Heroes is not the only game I'm stuck with for life and I'm sure other players before had experienced something similar and will be experiencing in near future as long as this type of mechanics persist in your game.
Those are my 2 cents, peace out.