Sounds like a weird incentivization for sure. Why not base the pension on the average over all the years worked as in many other countries? When you offer such incentives, people will naturally work in such a way.
Because you'll loose half a career's worth of inflationary salary rises that way. Also, women might work part time after having children which would skew the average annual salary down. Over a 40 year career, just from inflation alone, you'd be getting about half your final salary that way, even ignoring any increases later on from being better qualified or taking on more responsibility.
Mind you, in the UK, defined benefits pension schemes are very rare nowadays, but where they exist they are defined as a percentage of the final year salary with that company, so the highest 2 year thing seems a bit weird to me but for a different reason.
In the US, social security is based on the 35 highest paying years. If that system is good enough for social security, I don't see why we don't do the same for government pensions.
Mind you, in the UK, defined benefits pension schemes are very rare nowadays, but where they exist they are defined as a percentage of the final year salary with that company, so the highest 2 year thing seems a bit weird to me but for a different reason.