This is almost insane over the amount of specific nit-picking over card text and absolute refusal to just take how the rulings are and leave it at that.
First of all, blame the translations on some of them. That's what you have to deal with when things come out of Japan first where the interpretation is left open sometimes (see "Pulling the Rug" and why it was errata-ed just after release).
Second, blame the overuse of the word "Activation". When it comes to Counter-Traps there's only 1 Activation point that they are referring to: Whenever a Spell/Trap is placed face up on the field or whenever a player declares that he wishes to activate the effect of one of his monsters (or if an occurance happens that triggers the effect of a monster). Yes, there are other instances when we use "Activation" such as with "Ultimate Offering". In those cases though you are more "Using" the effect of the Continous Card. But the Initial Activation has long passed. Now that doesn't mean when an effect like that is used that it's not chainable (again, once Ultimate Offering is face up, you can chain the use of the card with itself).
So what's the difference between using a card like Pikeru's Circle of Enchantment vs. Barrel Behind the Door? Simple. Pikeru's doesn't have a timing requirement. Barrel does. With Barrel, you look for that moment of Initial Activation to see if Damage is guarenteed to be done. If so then yes you can chain it. That is why you cannot use it against Continuous Spell, Trap, and Monster effects since those don't inflict damage at that moment. They do so at different times later. It's why you also can't activate it against Ceasefire if say every monster is face down and/or all face-up monsters are Normals (because it could inflict 0 damage), or against Dice Jar (you could win the toss).
Past that, can't really help you if you don't like the wording on the card. However, the rulings are pretty direct and to the point (even with explaining why). Even in the case of this one:
"¢ [Re: Destiny Hero - Diamond Dude] Since the Spell Card itself is not activated (only its effect is), your opponent cannot chain "Magic Jammer", "Dark Deal", "Barrel Behind the Door" or any other card that has to be chained to the activation of a Spell Card.
And I know... I hear "card text" already. However, that ability to activate the effect of the spell card is basically a lingering state you choose to resolve, similar to "Last Will". Chainable yes, but not with Counter-Traps since (as already mentioned) they have a very specific window when they CAN be activated (Yes "Negate Attack" we see you back there, put your hand down, you're the red-haired stepchild of the group).
Now can this whole debate be put to rest since really it's just been nothing more than debating for the argument's sake and not really bringing any sort of enlightenment to the game.