While the basic game play found in Minecraft is very similar, each of the versions of the game has its own strengths and weaknesses, and finds its fan base for different reasons.
The PC version is the most expansive being the largest, and offers players a deep survival game play experience, being sought out by players who, in addition to that game play experience, also desire to play in an environment in which building machines -- small and large -- is part of the fun.
The PE version on the other hand has a very different focus -- that being extreme survival -- largely due to the reality imposed upon the player caused by its limited world size.
In basic terms the challenge in this version comes from the guarantee of an imperfect environment. There will always be more of one resource and less of others, and at least some of the resources will be very rare. Players who do not understand this -- or who are used to playing on the PC version -- often keep reloading a new game world in the hopes of finding a more perfect seed.
The point to that is that there is no more perfect seed -- the idea in PE is to create a game and then find a way to prosper IN that world. The relative scarcity of resources is the whole point to it!
In this sort of environment, when you do find a rare resource like Melon, Carrots, Potatoes and the like, you want to carefully conserve it as you set out to build the perfect environment for making more of it. And that is really the point.
Once you accept that premise you can start to enjoy the challenges of play!