I agree. The irresponsive key (delay in subsequent action) should be of top priority. Without it, playing Insane makes no sense

You forgot to add that it makes no sense TO YOU, as many people already finished their Insane runs (even more than once) with the key responsiveness as it is.

There are two different things at work here, and some people mix them up.

It takes time to recover from doing certain moves. It just does, and it should. Just try removing the recovery frames from a game such as .. say .. street fighter. There would be no penalty to throwing a hadoken .. so such a thing would simply break the game.

The other issue is the performance of the engine itself. Someone running at 60 FPS may be able to execute a roll when someone running at 12 FPS may not.
It has an obvious impact on those QTEs people complain about, but it also seems to affect normal gameplay ..
This is a problem that needs fixing, because a phenomenon like this is called a "hardware advantage."
People who are on sensible settings for their system are obviously penalised by having less impressive visuals, but should never be penalised in terms of what they can DO in combat.

But do you mean hardware specs in general or just keyboards? Because my system is mid-low range and I never encountered input lag problems.

Input lag is one thing, but I think the actual bug people might be referring to, is the one that causes all input to stop working altogether. It happens especially frequently if you use bombs often - sometimes the keys simply stop responding. Even the mouse-buttons cease to function. It's incredibly frustrating, and I'm surprised they haven't added a fix for it yet.

If it's intended as a recovery then it should at least be shown visually. For example after throwing a bomb, the bomb icon is in cooldown and player won't be spamming the bomb key hoping that they'll throw a bomb again.

Similarly if they are intended after rolling, players should be visually shown that any other actions be it casting signs, block, etc. should be shown visually that they are in cooldown.

If this was not shown then, other would be thinking that it was bugged. It's not the fault of the player. It's the fault of the developers that players was not informed.

That is just fucking retardedly ridiculous.

And your examples of why this is so are so incredible that my eyes can't even perceive them!

I agree that a cooldown timer would be incredibly distracting and may even cross into "patronizing" territory, but seriously. Show some respect.

It is intended to be patronising.
Why the hell should I waste my time engaging with morons?

You reload in a shooter. You can't shoot until the recovery is done.
How do you know when you can shoot? By the fact that you can shoot.

You do a double jump in a platformer. Gonna complain about not being able to triple jump?
Where's the indicator?

You get hit and stagger. In any game at all. You can't do anything until you recover.
Do you get an indicator? Well ... maybe a bloody screen, but that has nothing to do with recovery.

And I have already given the most important example of all.
Moves in fighting games have recovery measured in frames, and often you have a mere 1 or 2 frame window in which to do a link.
So how do you respond to a system like that?

Example: Darksydephil
That guy, when he plays games, does stuff such as throwing a projectile, then he says "nothing I can do" when he gets hit for it.

The problem is never the delay.
The problem isn't even him using a move that puts him at risk.
The problem is him being triply stupid for not realising what he's doing wrong, after doing the same thing repeatedly, then blaming the game for being unfair.

Stupid is stupid. I am neither obligated to, nor do I care to, respect anyone who is a fucking idiot.

To you maybe. It's not hard to add a recovery timer icon anywhere in the screen. Otherwise inform the players in the tutorial and manual that there is a cooldown and recovery of 2 seconds after ANY action.

Ok, if you're getting a recovery of 2 seconds, there's something wrong with your game.
You should be able to throw approximately 1 bomb every second.

Because everyone who you disagree with will tend to look like a moron? I'm not saying I don't agree with the recovery frames thing, because I do, but there's no need to respond like you did.

Let me tell you a little story.

One of my customers called me from out in the country, panicking about his printer not working.
I offered to walk him through fixing it over the phone FOR FREE, but his reply was "no! I can't do that! You gotta come down here!"
So I drove 2 hours out there, walked in, fixed the paper jam in under 30 seconds, then drove 2 hours back.

I charged him $270.

That is the right and proper thing to do.
Stupid needs to be punished, so it never happens again.

Ok, seriously, now you're getting too far. Witcher was praised so many times for lack of hand-holding and what you are suggesting is...I don't know, but it's just too much. There has to be a space in the game that you as a player fill with your skill, intuition or learning/observation.

At least I am a type of player that observes and adapts to the game's engine/combat system, not the other way round. It's about mastering what you are given. But I guess that comes from Quake 3 Arena times, when one had to practice for months to master certain skills within the rules and boundaries the game was setting.