I know for a fact that there's a section here on the forum specifically dedicated for suggestions for future updates for Minecraft Pocket Edition. But honestly, I feel that's a bit spread out, and would take quite a while for MCPE developers to search through. My idea behind this post is to collect those ideas in one general spot, make it a bit easier for Mojang to find some good suggestions without searching for hours. So if you have one, drop it here.
Let me go ahead and get some of the common and more obvious ones out of the way first. Pistons and Sticky Pistons. Mojang already confirmed them for 0.15. Another common one is commands. Ender Pearls was an accident in typing the 0.14 Beta description, leaving a good indication for them in 0.15. What else can you come up with?
A suggestion for the world of Minecraft as a whole, but I definitely want it in MCPE, advanced horses. The horses in vanilla Minecraft are rather dull and not life like. If you check out the simply horses mod. It added horses to the PC version before they were officially added. The horses in simply horses spawn in herds and the stallions would attack if the player got to close. Making it much more difficult to tame horses because you would need a lead to get the horses away from the stallion. Horses were also rarer, mostly spawning in plains biomes. The mod also added other cool features like wagons. Personally, I think it would be great to incorporate this mod into Minecraft Pocket Edition and the rest of the Minecraft world.