I would like collectables to return in SS, but this must be done right, otherwise, it'll just be boring. Searching for Poe Souls in TP was very boring. A few points I think that are important to make "fun" collectables:
1. Do something interesting about them
Instead of just collecting them for the sake of having them all (and, of course, the final prize) make something interesting about them, for example, the pictures in LA. Those photos were funny! I was always curious to find another one.
2. Don't scatter them randomly across the map
Put the collectables at key points, like at the end of caves, or in chests, not randomly in the middle of a huge field, where we could miss it just because we didn't pay attention.
3. Give some hints
Help the players by giving some basic information, like in OoT, when the map would indicate when an area was clear of golden skultullas, so we wouldn't waste time searching a single one in the WHOLE world map.
4. Not so difficult
It's pointless to have a collectable that's so hard to complete that almost no players will have the patience to do so. Besides, I think collecting all the heart pieces is already a pretty hardcore feat.
5. Possible before the end
Most people don't care if they can't get the reward before finishing the game. (AKA, Mirror Shield in MC)
6. Not such an overpowered reward
This one relates directly with the other two. It won't be good if the reward of a collectable completely spoils the fun of the rest of the game. In MM, for an instance, I completely smashed Majora with Deity Link. It sort of spoiled me from the epic fight. Happily, Fierce Deity Link is so damn cool, it overcame the downside!
And the most important:
7. Quality over Quantity
Instead of a 100 golden skultullas, or 60 poes, just give me 20 masks!
