Giant Trunade

Most people wonder, why this card is banned?
It only return all spell and trap back to the owner's hand.
so, it only provides 1 turn safety from potential table-turner back row cards like Mirror Force and Torrential Tribute which afterwards can be set again which is very different from Heavy Storm and Harpie's Feather Duster that destroy spell and traps, preventing them from being used again. But yet, Harpie's Feather Duster and Giant Trunade is banned while Heavy Storm is limited.

I don't exactly have the professional answer from Konami, but I personally can understand why it is supposed to be banned over Heavy Storm.

First of all, as both Heavy Storm and Giant Trunade gives 1 turn back row free, so that there are no risk in attacking, summoning a monster or etc. However, as Heavy Storm goes, it purpose is to remove back rows for good by destroying them which trigger the effect from cards like Starlight Road, Stardust Dragon, Shooting Star Dragon, Destruction Jammer and Geartown while these 5 cards effect cannot be activated in response to or after Giant Trunade effects kicks in. Playing Geartown definitely makes opponents think twice before activating Heavy Storm. They get to destroy your back rows, but gives you a 3000 ATK beatstick Ancient Gear Gadjiltron Dragon.

Another is because of the ability to recycle equip cards, continuous trap, union monster, Dragunity, Crystal Beast and cards like Swords of Revealing Light. Recycling cards like Premature Burial or Symbol of Heritage gives you huge advantage, giving you extra graveyard special summon. Most continuous trap that are used to special summon monsters, usually remains on the field if the monster bind to it is used for synchro, tribute, fusion or xyz summon. Such cards is like, Call of the Haunted and Limit Reverse. Though recycling union monster would be too much of an advantage, but recycling Dragunity or Crystal Beast is a whole different story. It certainly will give you hand advantage, but to tell you the truth, I wouldn't do that if I were you. It is more like a rare case that you might need to return Dragunity or Crystal Beast to your hand. Last is recycling cards that remains on the field a number of turn, such as Swords of revealing Light, Swords of Concealing Light and Nightmare Steel Cage. Supposedly, Swords of Revealing Light prevents opponent from attacking for 3 turns, but if you activate Giant Trunade on your second turn after activation, you can extend it to 5 turns. Against deck with a lot of power house but low destructive power, it is a great help.

On top of all that, I strongly believe that the main reason Giant Trunade is banned is due to back row removal without triggering cards like Starlight Road, Stardust Dragon, Shooting Star Dragon, Destruction jammer and Geartown.