Well responded Mr. Sercril, I was worried my assumption would fall on deaf ears. I assume that since the assumption for which my argument is based upon, the notion that 'brony' is a term with a negative connotation, obviously would not sit well with some people. Before I even posted my response I knew there would be a wide variety of people who would disagree with what I'm saying, I expected this much in the same way I was bracing myself to be called a chauvinist because I questioned the need for a female equivalent term.
So I guess I'll respond to your major points.
Ok so as for necessity, I really just think of "brony" as being shorthand for fans to identify themselves to other fans. The term itself can be traced back to when the show first aired and posters on /b/ who were posting about ponies were banned for their posts. They used it as a term to separate themselves from other posters.
As for the term"brony" being an insult, I must ask, who have you been talking to? Of course it's no secret that "brony" has had somewhat of a negative connotation on the internet since the first posts on /b/ but nothing about the term itself is intrinsically insulting.
And who, may I ask, are "the vast majority of individuals"? Because if we are talking about the general populace then I should remind you that the very act of being at all interested in anime is considered childish and humiliating by "the vast majority of individuals".
You answered your first question in the first paragraph. I myself am no stranger to /b/ and I was there when the show first came into prominence and thus the board was flooded with a torrent of Pony fans. I will not lie to you; my first experience with the "brony" came from those experiences on /b/. What you neglect to mention in your first paragraph is why the "bronies" were banned from /b/ in the early days, while my memory is cloudy from back then I do vaguely remember the fandom effectively spammed the /b/ forum to hell my endlessly posting numerous pony threads, hijacking other unrelated threads and generally acted like annoying obnoxious twits, which eventually led to them getting banned en masse.
Now you might think it is unfair for me to judge a fandom by the actions of a singular group of fans, and you'd be right if it wasn't for one simple thing you mentioned above. The term "brony" was created by these aforementioned fans, and was eventually adopted later by the broader community at large. As for the last question, I myself know a few fans of MLP: FIM, and I have watched the series to some extent myself, one reoccurring theme I have noted amongst all of the people I know who do are fans of the series is they always refer to themselves as fans, they never refer to themselves as Brony's because they do not wish to be associated with that fandom.
Personally, I think making the connection between "otaku" and "brony" is just plain wrong in the fact that there really is none. I consider myself a brony. I have watched every episode of the show twice, own 3 Fluttershy figures (2 were gifts), and carry my laptop in a messenger bag with Derpy Hooves on it (derpy delivers mail in the show, I thought it was appropriate). Does this make me crazy? Fans who call themselves "bronies" are just that, FANS. Not crazy otaku's or NEETs who shut themselves off from society and devote their lives to the fandom, just simple people who like the show. Obviously, there are crazy elements of the fandom, but I challenge you to find me a large fandom without at least one crazy fan.
I, and all the level-headed bronies I've met, don't consider the term to be negative at all. It's just an identifier. If you think the term is negative, then that's your prerogative, but I urge you to use the term based on what it was when it was created and how members of the fandom use it. Not the way trolls on the internet use it.
Maybe the connection I made between Brony and Otaku may have been too extreme... however as you yourself noted there are always obsessive fans within a fandom, the problem here is there is no differential between fans of MLP: FIM, both the average fans and the more obsessive fans are lumped together under the same banner, "brony". When it comes to anime fandom, one can either associate themselves as a fan of a particular series, franchise, genre, studio, or just a fan of the medium in general. "Otaku" is the term used for a person who has a serious compulsive obsession with one of those above options, and it considered one of the most undesired personal quality for people in Japan. (Various polls of Japanese women found online, asking about personality traits they dislike/wish to avoid in a potential partner, usually have traits associated with the Otaku subculture up the top of the list by a wide margin)
So what does this have to do with me liking Bronys to Otaku. Even from the paraphernalia that you have from the franchise does not necessarily mean you are an obsessive fan, my issue is the fact that you are adopting a term for yourself as a fan of that series without really understanding the legacy behind that term, very much like the misguided westerners that went around joyously referring to themselves as otaku without really understanding what the term meant. While the latter can be chalked to a culture difference, the former can be put down to the ambiguity of how the term "brony" came to be.
As I mentioned above we both believe the term originated on /b/, the problem here is my recollection was the term was used as a derogative term to insult the fans of the series while they went about trying to flood the board and generally acting like morons, while at the same time the very same individuals started using the term to refer to one another as if it was some sort of badge of honour, but regardless of how that started the fact remains the very first instance that I was introduced to the "brony" fandom was during this period, and as they say, first impressions are everything.
I guess in finishing I have one question, I can tell by your response these examples I have given are not a fair indication of you and your fellow "level-headed bronies". My question is why do you need a term to identify yourself as a fan? Why can't you just refer to yourself as a fan of the series, or a fan of the franchise. By making up words to indicate your level of fandom people are going to start expecting the worst, especially when that term's origin isn't exactly good. You can be a fan of the series and not be a Brony, the problem is many people are assuming that is not the case, that doubled with the terms troublesome origins and you get why I've assumed the term "brony" was derogative.