I have been playing the game for some days now. To make the whole experience much better, they only need to change the difficulty of the single player towers.
TBH the grind itself is not as bad as it sounds, the problem is mainly that the towers you need to grind are extremely hard to complete, frustrating and plainly not fun most of the time.
The towers actually give you decent amounts of ingame currency, it's just that they are sometime impossible to complete.
That means, they don't even have to change anything about the monetization or currencies itself, but only the difficulty of the towers, to make the game immensely more rewarding very quickly.
At least for a hotfix-type of situation.
they should do the following asap:
1) lower difficulty in the towers of time or let players choose difficulty in towers of time, if someone wants to play on easy, let them play on easy...maybe give more rewards for harder difficulties but don´t mandate to play ultra hard towers
2) reduce the cost of the Krypt chests or higher Koin gain for playing towers
3) make the negative modifiers affect the AI too...part of the fun of this stuff is that the AI is also affected by blizzards, rockets and other shit and not only the player character. and make the assists blockable!