I'm not sure the Tower works the way you think it does. I'm in the top 10 with a pretty powerful deck (as long as I can get 6 matching gems in the first turn, I can't lose), and I haven't spent a dime on this game. There's no prestige or patronage involved, just a lot of time. I just keep fighting and fighting, and doing a whole lot of "Remove chest". Mostly Common, but I've had to burn Rare, Epic, Legendary, and even Mythic chests in the process too.
All I'm suggesting, is that the "Remove chest" option for chests be made available for chests currently occupying a slot:
That way, I can remove Common chests (which I have no use for) to free up slots, so if I get a chest I want/need, I can keep it, rather than having to wait an hour or longer for the chest timer to tick down (while the event timer is also ticking away) in order to free up a chest slot.
The ability to open a chest early using jewels (or items acquired in the Colosseum) is fine, but it doesn't fix the problem when event mission progress is gated behind acquiring a certain level of chest which is governed entirely by RNG. And I'm not looking to open it anyway, I just want to remove it (and its contents) entirely. You can do that for free when you win it (if you have no open chest slots), so why not be able to do it anytime afterward?