When you redesign something, there are always tradeoffs.  Very rarely do all the stars align and you improve all aspects of a design.  When improving one thing, something else must give.  In redesigning our voting system, it is no different.  Our current FPTP system is simple, accountable and stable.  The major drawback with our current voting system is that there is a perception that not every vote counts.  How do you make every vote count and keep all the advantages of our current system?  So far nobody has come up with a compelling answer to this question.  PR seems to be the most strongly favoured alternative.  PR leads to shorter unstable governments like the ones in Italy and you lose the accountability of a directly elected MP.  You then must look at some form of Mixed Proportional to maintain stability and accountability.  Mixed Proportional gives you a complicated mess; you lose simplicity.