Jake is partially right(I don't support multiple member disticts), especially on the non-partisan thing.
Anyways, Even if there is "open list" PR, the party just chooses those who go into the open list, and the people only choose the order.
This also removes the accountabiity to a certain constituent body, and before you mention MMP, know that in Germany even constituency MPs don't care about constituent services at all.
Well that has alot to do with the political culture of a country. If you're politicians just don't care, they just don't care. You can make the same assesement of American political leaders as well. Besides giving out money to where they represent they really don't do anything for their district. Politicians everywhere want to stay in power no matter what. Sometimes and in some places that means kissing up to the party and towing their line, in some places and at other times it's kissing up to your electorate. Then you have some who do both. It happens in America, it happens everywhere.
Remember that most (not all) German constituency MP's would have been elected anyways if the state list vote had gone the same but they had lost their constituency. The constituency vote in Germany is pretty much a scam. In practice, we have pure national pr.