Besides the obviously snide and holier than thou tone of the OP, there's a few reasons why I don't think that several of the arguments to nerf are valid.
The first is level of contribution. I honestly like that there are noob friendly kits for gold. I would not say I'm an "elite" player. I've never soloed platinum with a volus, or topped a gold scoreboard using only a FQE with a Locust or whatever. I can say that every match I join, I will contribute to in a meaningful fashion. I will be outscored, and I will outscore people as well, but during every single game, I will contribute. Kits like the AIU, TGI, and Juggy allow players who wouldn't normally be contributors a way to make themselves useful on matches where they might be a drag. I'm cool with that. This is a co-op game after all. Doesn't anyone remember the days when being a crappy gold player meant dying too much? So BW makes a few kits that allow those people to contribute a bit more, and how does BSN react? By saying that people aren't dying enough.
The second is boredom. People who call for nerfs generally say that they're doing it to save us all from boredom. This is noble, but unnecessary. Yes, we will see a lot of AIUs in gold lobbies, just like we saw a lot of TGIs before them, and Krysae toting GIs before that. This will wind down because why? Boredom. My favorite class to use is the N7 Destroyer. It's awesome being like War Machine, pounding out tons of weapon damage and carpet bombing or if I'm feeling crazy, shooting missiles out at will. Do I use the Destroyer much anymore? Well... not really, because I'm kind of bored with it. I used it a lot, and now I've moved on. No matter how good I was with the Destroyer, no matter how many credits I earned grinding out matches with him, it's easy for me to move onto another character because it's boring to play the same thing over and over again. Don't get me wrong, I sometimes like firing up Devastator Mode and turning things into goo with my PPR, but really, the very thing that nerf advocates want to prevent actually balances the use of characters.
The third reason, is fun versus efficiency. As I stated a bit before, my favorite kit is the N7 Destroyer. I feel like I'm pretty damn good with my Destroyer. When I do choose to solo, he's the class I tend to try out first. I recognize that as far as efficiency is concerned, he's probably my best kit. However, due to the fact that I've played a lot of games with him, he's not my most fun kit right now. That would be the Krogan Warlord (smashing Scions is endlessly great). Nerf advocates assume that becaus a kit is efficient, it is the most fun, and since fun is the highest factor in determining why people play games, the most nerfworthy kit is the extremely efficient kit. Again though, boredom is key in limiting this. You might say that the AIU encourages bad habits, and players who use the AIU in gold matches will only be able to use the AIU in gold matches, and because of that, eventually everyone will only be using AIUs in gold matches because it's the efficient thing to do. What I say is the more likely scenario, is that here will be players who will never regularly play gold or platinum. The step up just isn't worth the consumables and the lack of contribution, so occasionally, they might play a gold match with the AIU/Juggy/Whatever broken class of the week for a quick shot of credits, and then go back to what the enjoy playing, which is silver or bronze. I don't see what's wrong with that.
All told, the attitude of the OP is partially the reason why nerf threads are met with such venom. I will discuss valid reasons why things should be nerfed/buffed, but I don't even want to know what kind of person thinks that they know how to "protect" me from a video game that I play for friggin fun. High horse... get off it pls.