First and foremost, this is my first fanpost, so please go easy on me. I lurked for quite some time reading articles and comments before I signed up fairly recently. Second, I would like to thank MMALOGIC from the UG forums for piquing my interest in this idea.
I think if the UFC considered featuring one or two weight classes it would help the promotion, the fighters popularity, and ultimately the fans.
The injury problem has been a major factor in the decline of the UFC in 2012, and having tons of fighters from one or two weight classes would solve that I think. If one or two injuries happen, as is expected these days, it wouldn't be as big of a deal because you would have almost the whole top ten or fifteen fighters to replace them with. Even if a major star is lost to injury, the cards would be so stacked that they would still sell well.
I would personally prefer one weight class per card, but I admit there will be some major logistical problems with that. I will focus on that a bit later. If there were one class per card, from the prelims up to the main card, each fight would be a progression toward the belt. The co-main would be for the next contender, and so forth. Every time you see Anderson, you see Weidman. Everytime you see GSP (or Carlos in the case of his injury period), you see Hendricks. Even if some fighters are injured or don't fight as often, the idea still works. The casual fan can make sense of the title picture much better, and you wouldn't need to resort to lame grudge matches or good guy vs. bad guy, or the full UFC hype train behind guys who don't deserve it because they are a loud mouth. People would be demanding the worthy challenger fight the champ, they wouldn't get away with Sonnen vs. Jones or Diaz vs. GSP.
The UFC would also benefit because IMO, they aren't very good at promoting new stars because of the "brand over individual fighters" motto they employ. The fighters would build their name, because again, every time today's stars fight, the up and comer in that division is on display, and the casual fan can see his progress, and where he stands in the division. The UFC would need to make an official ranking system, and they can use that to show the casuals where everyone stands, and the matchups would reflect that. Currently, some casuals will only order a card if it has their favorite fighter, and can't make sense of the title picture, they just know "I know who that guy is" or " I like that guy". That is basically what I hear when I watch at a bar, I never hear "that guy is 2 fights away from the title shot".
More realistically, a 2 weight class system would probably be more feasible. The strong established weight classes can support the weaker ones. Such as WW and FLW, HW and BW, etc. If there were 6 matches on the main card, that's 12 top ten fighters you can put on there, 3 fights per division. The prelims can be split as well, for a chance to move onto the main card the next time their weight class is up. If someone is injured, they are easily replaced and will need time off anyway, and they can just be on the next card that comes around. Their weight class would have fights about every 3 months if the straw-weight div. is added I believe, and the Women's Bantamweight Ronda Rousey title match can be a feature match. Some of the weaker divisions can be added to the fuel and FX cards more than PPV.
There are definitely logistical problems, no doubt about that. There would be fewer cards, but the quality of them would be so much higher, it would be worth it. It would also alleviate the cries of oversaturation. I'm just throwing the idea out there that I believe could result in some awesome cards and fix the injury problem.
Someone that is paid by zuffa can figure out the logistical side, the wheeling and dealing and so forth, but I believe this could work if implemented properly and one or two weight classes at a time. A weight class that doesn't have a champ that sells well could test the waters, and the lightweight division would be my choice, since it is deep, and if it did great buys, it would be a great indicator.
I know some people like their cards mixed and matched, and want to see more than one or two weight classes featured if they attend fights live, but the bigger picture would be in some major PPV sales, and I think these kind of things can be worked out. It's much better than the alternative, which is boxing style top heavy cards, gross mismatches, undeserving title shots and pro-wrestling talk. It would legitimize the sport in many people's eyes, not that a lot of hardcores care, but that extra revenue could bring in some serious athletes and instead of the sport stagnating it could thrive.
Thanks for reading.