Sync makes a wonderful addon to hardcore mode, if perhaps it was a little more expensive to make a new shell. As it is now, as soon as you can make a constructor and a storage unit, the pig power to make a new shell is nothing.
Piggy makes a great potential for instability, or for a special event / special series. It doesn't make a good item for a normal world. Still, you might have a scripted event for something special that is happening 1,000 blocks away from your main base that you visit occasionally for some special reason.
Morph ... seems like both "hey, look what I can code / look what can be done" (which is interesting), but also excessive with "Flight for free, or underwater swimming for free, or ignore fall damage really cheaply". Actually, do zombie pigmen give you lava resistance? If so, add that to the cheap list.
Hmm ... Never thought to try an enderman, can you teleport? Any control?
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Pocket dimension, immibis' power mod, and a couple of others look like "How much of an existing full mod can be done in a weekend". Not that this is bad -- if the challenge is "what can you code in a weekend", then it's a fine entry. But as for a mod that you want to play, there's more complete existing versions of those.
But if the challenge is "what can you code in a weekend", then piggy is perfectly fine. And it probably will get more play than those others.
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If anything, I think that things like the mini-games, or the first person shooter conversion, should be judged differently than "This is a mod that you are expected to add to your world and play with for a long-term play". In other words, categories for "one off" sessions, versus "long-term play" mods.