Uhmm... no?! Premium is a beneficial package given to those that pay money to get this. It's the gamer's choice whether or not he/she wants to pay money for it. If they choose not to pay and buy it, they have no right to complain about others who did and get to use this premium package. =)
But... if you manage to achieve everything in-game without using the premium package, you are in fact better than the ones who need it. Think of it that way?
Premium content, in my way of interpreting it, is just promotional. It is a way to interest users and get them to pay the developers. They put awesome stuff in the premium which is better than the basic package so that they get more money (noone works for free you know). However, for people who cannot afford to pay for it (including me in ALL cases), those people feel disheartened and feel as if they have not had the full experience of the game and feel even worse when they struggle on a level while everyone else bypasses it with ease with their fancy equipment. But then again, if you manage to beat the level without buying items, you are in a way more skilled than the people who did pay. You did not require any extra help but still got the same result so you did make yourself a better gamer compared to others. But using premium advantages and equipment is definitely NOT a form of cheating. You paid for it, so why would it be wrong to use it? It is your full right to use it however and wherever you want.
I've completed KR without the premium content many times. It's not that I need it to win the game, it's just that it's fun to have extra heroes and stuff like that.