The problem with "Instant OFF GCD" abilities makes combat feel less rewarding.

[Kanzer]

You're missing the point completely. Instants such as those mentioned are by design reactive emergency abilities. Making it so that success is dependent on predicting scripted encounters through repetition is simply boring and uninspired when compared to being genuinely based on fast reactions during a dangerous moment

If this is intended, It's a very dull design.

Or maybe you're missing the point, since a SE rep has even posted in this very thread telling you that your perception of how these abilities should work is INCORRECT and does not fall in line with their design.

The problem is you're just too hard headed to accept that and want it to work exactly how you want it to, instead of simply adjusting to it and bettering yourself to handle these situations that are giving you trouble.

The problem lies with you, not with the design of the game.

Edit: Also, still waiting for those specific examples mentioned in the above post. Stop dodging and actually back up your claims.