Beside toy promo, what's the point of COMBINING?

I saw the Unicron Trilogy lately and they sure love their combining! Especially in Energon. It's completely ridiculous.
But first, lemme tell you of the combinings that make sense and are awesome:
Multi-bots that combine to create a new character that is a monstrous behemoth à la Devastator. This one is a given.
Optimus Prime, combining with his trailer (or drones) for a super mode. When Prime is not fighting or he want to be nimble, of course he would want to stay small. Then, when the fighting get tough and he have the room, it's upgrade time!
Next, the combining that is acceptable and kinda logical:
Optimus Prime combine with Jetfire. Prime go to a super mode that give him flight capacity. Super Mode OP that fly is cool and all, but he lose the use of a another powerful and competent soldier... Honorable mention to Armada OP combining with Armada Overload. Admiting Overload is a brain-dead idiot, it make sense he's more useful as a giant targetmaster.
Finally, the combining that is completely pointless and stupid:
All the other combinings in Energon.
"Ironhide! We must fight hard! So gimme a piggyback ride! Weeeeeeeeeeee!!!"
Honestly. What the hell? Instead of having TWO GUNS and TWO SOLDIERS fighting, we only get ONE SOLDIER with ONE GUN. Without anything gained beside making a somewhat bigger target. Each times it happen in Energon, I facepalmed.
Honorable mention to Cybertron OP using that tiger bot as an arm. What's the point?
So, what do you think of this? Can you play the Devil's advocate and defend the pointless combinings? (remember that the "to show the toy's gimmicks" argument don't count)
Any other combining you find pointless? Any combining you want to see?
Why?
But first, lemme tell you of the combinings that make sense and are awesome:
Multi-bots that combine to create a new character that is a monstrous behemoth à la Devastator. This one is a given.
Optimus Prime, combining with his trailer (or drones) for a super mode. When Prime is not fighting or he want to be nimble, of course he would want to stay small. Then, when the fighting get tough and he have the room, it's upgrade time!
Next, the combining that is acceptable and kinda logical:
Optimus Prime combine with Jetfire. Prime go to a super mode that give him flight capacity. Super Mode OP that fly is cool and all, but he lose the use of a another powerful and competent soldier... Honorable mention to Armada OP combining with Armada Overload. Admiting Overload is a brain-dead idiot, it make sense he's more useful as a giant targetmaster.
Finally, the combining that is completely pointless and stupid:
All the other combinings in Energon.
"Ironhide! We must fight hard! So gimme a piggyback ride! Weeeeeeeeeeee!!!"
Honestly. What the hell? Instead of having TWO GUNS and TWO SOLDIERS fighting, we only get ONE SOLDIER with ONE GUN. Without anything gained beside making a somewhat bigger target. Each times it happen in Energon, I facepalmed.
Honorable mention to Cybertron OP using that tiger bot as an arm. What's the point?
So, what do you think of this? Can you play the Devil's advocate and defend the pointless combinings? (remember that the "to show the toy's gimmicks" argument don't count)
Any other combining you find pointless? Any combining you want to see?
Why?