Well, first of all, the term “competitive”. Competitive in the context of gameplay means the gameplay’s suitablity for competition. You can’t really say “this is competitive” or “this isn’t competitive”. The term only works as a comparative term (e.g. “this is more competitive than that”). Balance and simplicity do fall under this as balance is one of the factors that decides how suitable the game is for competition. As for simplicity, this just usually -Yoink!- competition as a game simple with the amount of content and deep with the usage of the content is often better than a game complex with the amount of content.
What do armor abilities, loadouts, specializations and ordnance drops do then? Well, first of all, I can’t answer the question “what do they do?”, no one can. I can only answer the question “what will the potentially do?”.
Armor abilities and loadouts kind of go hand in hand. The concepts of different armor abilities are very good, some of them are quite amazing. However, having them in loadouts destroys the whole concept. When giving players abilities they spawn with, abilities that are different for every player, you really need to balance them carefully. The balancing is really, really hard when you look at the big picture. When the abilities are fundamentally different in function, you might very well end up with a situation where the armor ability you pick-up has too big of an impact to gameplay in which case it easily becomes like rock-paper-scissors when you can’t really predict your opponent’s choices. Suddenly, all consistency is thrown out of the window. And consistency is a very important concept for competitiveness of a game.
However, the inclusion of armor abilities in laodouts is actually more problematic. You see, all the abilities would work better as map pick-ups than abilities you spawn with. Active Camo is the classical example because everyone knows how well it works for competitive play as a pick-up. However, when you give it to the player off-spawn, the player suddenly isn’t restricted by the location of the power-up, but they can activate it anywhere they want at any time. Not only does this make it the ultimate camping tool (the complete opposite of the movement encouraging power-up), but it also makes one point of map control less relevant. Active Camo isn’t really the only ability that would work better without loadouts, this applies to every single armor ability we’ve seen this far.
Ordnance drops are a controversial subject. They can be completely harmless if they are predictable and always drop to set locations. However, in case there is too much unpredictability to them, they will become random. Randomness, again, is one of the things that can often hurt competitive play, thus making the game less competitive. Another problem is having the drops on symmetric maps. Symmetric maps require symmetry everywhere. What this means in terms of weapon drops is that if you drop a sniper on one side of the map, you also have to drop one on the other side. In other words, this pretty much limits the drop points to the axis of symmetry of the map, making the whole system limited. Again, a system that spawns weapons consistantly at set locations is much better for competitive play due to consistency.
As for specializations, I really haven’t herd anything about them, so I can’t help you understand there. However, I hope this helped you understand why the new gameplay elements are likely to make Halo 4 less competitive than previous Halo games.