I like the idea of more secondaries, but MCSG is revolved around the real Hunger Games. Heck, even the fishing rod is technically found in a real HG, even though the common strategy with it is a bit ridiculous.
There are two issues with adding these types of items.
1) They're not always fun. Cobwebs could be severely abused with a tryhard community like ours, and I doubt TNT would be much better. Sorting your inventory becomes harder, and if you want everything in your hotbar, you'll have:
a sword; a rod; a bow; an FnS; cobwebs; TNT; golden apples; food; arrows.
That's 6 slots just for weapons, and if you want more food, an extra FnS, or a boat, you don't have enough room to be at full potential.
2) We like our originality. If MCG decided to start changing everything to suit what people wanted, this game would be much easier. One of the signature traits of our SG is us "sticking to the books" and keeping things based mostly on skill. Here, the better player will win often. On servers like the Hive, one lucky use of a secondary can lead to a noob winning the Survival Games with very little work put in.
For these reasons, I doubt that this would become a feature anytime soon. But it's all a matter of what you like. One of the best parts of servers is that they're not all alike, and that lets you choose what is most fun for yourself. I wish you luck in your Minecraft days!