[UI changes] - How to increase spell cast responsive

Hi.

At current patch 2.6 you can't do anything while casting.
For example, if you cast fireball and immediately after you will try to use frost wall - the second spell will be ignored. Due to the character was busy be casting fireball. No matter your cast speed value, increasing cast speed will just make this gap shorter, but it will still exist.
Another example - using movement spell while walking. The spell will be ignored too due to the character was "casting" walk.

This is not an obvious mechanic. In the middle of a fight for me it's hard to understand why one spell was casted successfully, and another one wasn't.

When I noticed this first time, I wanted to ask developers to make an queue: queue of orders from real player to in-game character. But now I'm not sure: this queue can make enormous changes to the gameplay.

Well, because all players will receive second quickly accessible hotkey bar from swapping weapon. This can force us to use more spell combinations. Ofc, we can cast spells from both bars even now, but this is too timing business: plus-minus ten milliseconds can make a huge difference.

Now I'm thinking about one build, and this UI stiffness tires my hand.

So, I want to ask devs and community:
* Is it a good idea for Path of Exile to have something like a queue of orders?
* If yes - why, if no - why.
* How do you get through this restriction? Do you at all?

P.S. Maybe this was already done in 3.0, idk.