Governments at best produce majority rule although some say greatest utility for all is possible

What does it take to make laws?

you just need to pass bills in the legislature.

How is that done?

A majority of members present in the chamber at that moment vote in favour of it (or conversely do not vote against it).

Bills are passed (or blocked) in legislatures by a majority of the members present at that time.  ayes and noes determine whether or not a bill passes, not some greatest good or utility.

How a legislature operates is separate from how it is elected.

Whether PR is used or plurality to elect the members - a majority of elected members pass or block bills.

Whether multi-member districts or single-member districts are used relates to district contests, not government performance -- but only if votes are pooled and multiple member elected can you have science-based fair elections - PR. So the framework of the district contests does help determine performance of the government.

There are four stages to elections - 

-voter's vote - X vote, ranked vote, plural votes or single (whether voter casts vote for his preferred choice or votes in line with district expectations to get best chance to see vote used to elect someone, the dreaded strat. voting - vote in favor of the least hated of the big two.)  and transfers if STV or IRV are used

-a district's result, plus top-up if MMP is used.

-make up of legislature - majority is one party or multiple parties?

-cabinet selected, and party caucus (or caucuses ) who have majority.

Election does not produce measure of greatest utility, it elects members -

and its effectiveness and democratic value is determined by counting how many votes are used to elect winners and how many were not, how a party's share of seats reflects its share of votes.

We might wish government operated to produce greatest good to greatest number or max. utility, but influence of privileged minorities (rich and powerful) trump the needs of the the masses.

But voting in election is done for a reason - to make government accountable to voters. if election results do not reflect votes cast, then it is futile experience. voters cannot rely on some social conscience that the government will maximize utility for all, if whole blocks of voters cannot even elect a representative to speak on its behalf. PR merely ensures that each substantial block of voters is able to elect its due share of members - whether those members will have any real power is up to the make-up of the legislature and how the government cabinet is chosen. An election system where most votes are not used to elect the winner is patently seen as unfair and that drives the  will to PR. A vote that is ignored and elects no one is unsatisfying. many people shrug it off as it is so common but others do see it as unfair.

If governments "attempted to maximize the net utility of all voters," then there would be less cause for complaint, but usually governments reward friends and punish enemies, in part in order to be re-elected  - power corrupts, and they do as little as possible for parts of the state or country that did not support government.

And regional polarization is produced by plurality system caused by waste of votes, and that makes it easy for government to know where geographically they don't need votes,

but under PR, 80 to 90 percent of valid votes are used (and those votes are satisfied at least to the role that they played in the election), and the government sees that its support is stronger in some places and weaker in others but every vote counts.

Every seat is safe and unsafe to a degree, all parts of state or country are seen as important.

The benefits of PR work at three levels

-a large proportion of votes are used to elect someone. STV allows transfers from party within party slates and also across party lines; list PR allows limited transfers within party slates.

-in each district a mixed group of members are elected. (or some other form of vote pooling for fairness)

- in the legislature if no party has majority of seats, then inter-party cooperation is needed to pass bills that broadens the usefulness (utility?) of the government to more than just one party's voting block.

(the dream of a cabinet composed in PR fashion from all or most parties was described by Alberta Labor and Farmer MP William Irvine back in 1920s, but so far is nothing more than a dream)

Without PR, you have minority of voters determining majority of members and thus government.

No good, not democratic.

If governments were angels, then PR would not be so important

but governments behave no more honorably than you would expect,

and that is why democratic accountability to the majority of voters is so important.

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further discussion:

laws passed are produced by the majority in the legislature, not some average or concept of greatest utility.

present politics is full of policy lurches (would the "greatest utility" change so much as that?)

and laws passed by legislative majorities that are not supported by majority of voters.

the idea that any election system would produce a representation or a legislature that reflects the average or satisfies all is like the myth that a single member in a district can represent all the voters in the district.

the member can only vote yes or no on each question, and that means what he says must disappoint some voters. in fact if a representative represented all or satisfied all, irrespective of who he is or who the voter is, then we would not need elections at all - any member would be fine for all voters.

But in fact elections matter, and that is why we need a fair system -

if we don't have proportional representation, we have disproportional representation.

if we don't have proportional representation, we have minority rule.

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