There have been many suggested changes. Merely improving the odds does not eliminate the risk of doing 30, 60, 90, whatever summons without getting a good hero.
My suggestion for an improvement is here: Something a little more certain for your spend - shards? - #37 by Kerridoc. The new emblem system is along these lines—small, frequent and random drops that reward grinding.
Any change is a tricky balance. If you make it more certain that spending a lot wins a good hero, then it seems likely that there will also be reduced odds of getting the hero on a limited budget. People who spend a lot should have more goodies, but not all the goodies. This issue has also been discussed at length and shouldn’t be rehashed here. See, e.g. RNG Taken Too Far!