Dodging in Games

I need to know. IN any game is dodging an important mechanic to have? Should it be usable in any tabletop game? Because I was in one where I could've dodged from a attack and I couldn't it was a instant hit.

FableTop's built in rule system allows for use of Power Points to avoid the result of an attack, whether by block, dodge, or magic.

Outside of that, you're asking about custom rules. I'm sure you'll get a million and one reasons as to why custom rules to allow blocks/dodges for free/at a cost are good/detrimental, but at the end of the day, I think the answer to your question is:

"Yes."

Dodging is an important mechanic, and one that is included in the FableTop core rule system.

Yeah, I'm in favour of minimal dodging by use of power points only. (as the Fabletop rules say to) Whilst it may seem 'fairer' or 'more realistic' to allow dodges for every attack at no cost, there are a few problems;

1) More dice are being thrown per attack - this makes the result more predictable
2) Sometimes, when players aren't paying attention, the damage avoidance rolls come with a delay, and if enemies are dodging too, they take many more attacks to defeat - this leads to combat being drawn out thus slowly the progression of the plot
3) Now that players can take 1 or 2 damage off most attacks, you need to scale up your toughest npc enemies - to reliably put the 2 damage back on this is SIX more combat dice needed. You'll quickly hit the 10 dice ceiling and be unable to make your next boss stronger than the last one.

Oh, I should also mention that when I joined the site, dodging had not yet been added to the rule book. You just took the damage the enemy rolled and to be honest, that worked well enough.