I don't see the issue with Amons backstory, I wouldn't even say that missing out on the opportunity to use it to rally the troops was a problem (considering the zero run time they had left when it was revealed) a big deal but to each their own. Personally I thought that his story was pretty great and interesting, and a lot better than had he simply been... some non bender who could just take away powers and ignore blood bending for no real reason.
It's either a pummel fest or everyone runs away. Fucking thrilling fight, when everyone's staying at an absurdly long distance from each other and trying to maybe get sneak attacks. Except, as soon as you step into Amon's range, he has you, and he has a huge range. Also, he can make people move slower through his bending (which is why he always seemed so fast).
There is no possible way that you can convince me that this would be an entertaining fight. It would effectively be a non-fight, which is what we already got. Amon is broke as fuck. They would have to create a bullshit scenario, which I've seen a lot of people were convinced already happened when Korra unlocked her airbending.
There is no world where a character this broken gets a good fight unless said character is fighting another equally broken character.
I still don't think that Amon not being able to provide a 'fight' fight is an issue, but:
It's all in the execution, it doesn't need to be a 'fight' a la Korra versus Zaheer, it just needs to be entertaining to the viewer. Amon can be distracted, overwhelmed, blindsided, just like anyone else, maybe even more so because he hasn't honed his fighting skills traditionally. Just look at how a Handicapped Korra and her father were fighting Zaheer and how they almost flat out killed him: Misdirection. You don't need an equally broken character to beat Amon, he got taken down by his brother blowing them both up because he didn't see it coming. Why not put him in circumstance that limits the effectiveness of Amons blood bending, then you can have a full on punchy fist fight as well with a full on Team Avatar versus a somewhat handicapped Amon. I mean worst case scenario, Future Industries could have been developing some kind of chi blocking cocktail that supresses bending abiltiies (under Asami's father), and you has the big play misdirection to hit him with that first, weakening his blood bending and allowing for a full on fight fight.
And there is always the issue that Amon must be aware of those around him to blood bend them (line of sight would play a factor here if he wasn't aware to begin with). or is he just passively aware of anyone in his aura? Get him in a lights out environment or one with a lot of sight blockers and you could have a very interesting fight using light, darkness, misdirection, switching in and out, and even some Future Industries night vision tech (which the equalists already have if I am not mistaken).
Amon is powerful as fuck, but you can create fight scenarios that put him on the defensive. I mean, let's not forget that Korra knocked him out a window with Air Bending at the end of season 1 and he was just standing there bieng like 'omg what do?!'.
Really the take away here is that I love Amon.
Actually I would have liked to have seen a bending inhibited Amon versus a bending inhibited Korra just for the choreography and brutality. We got a taste of it when the equalists bombed the pro bending arena (Korra versus Amons Lieutenant) but a true hand to hand Korra fight would have been something to see. Or Amon /w water bending versus Korra w only air bending and tons of close up melee.
Plus that scene is one of the best in the entire franchise IMO.
Also,
I always reference this scene (in my head), Korra shooting the fireball into the ship, when people talk about how LoK is lower powered than AtlA. I mean yeah it is absolutely true, but it's all in the execution. That fireball might not have been as big as ones we saw in TLA, but damn if that moment wasn't insane; seeing everyone else in the ship knocked back off their feet, screaming, and all the loose bits in the cabinet flying about while Amon calmly steps off and looks down at the Avatar.
