"The political system in terms of FPP is broken, it leads to a two party system"
And as such, the two parties DO NOT want it changed.
It took a lot of effort to get New Zealand switched over to MMP - and only because politicians from both main parties were silly enough to make noises in favour of it when opposition. This was used against them when they got to power and tried to sweep it under the carpet.
It's rather telling that when NZ switched, the establishment tried very hard to convince the public to vote to stay with FPTP or go to the least proportional system (the same one that was on the referendum here) - only to find out in a fairly overwhelming turnout (twice!) that the electorate wanted a change and they wanted MMP.
The extablishment also tried to convince the electorate that they should go back to FPTP after the 20 year trial period in a recent referendum (or change to another form of Proportional representation) - and found out yet again that the electorate LIKE this new form of representation very much thank you and would like to keep it.