> Those complaining are a minority, or else they would have representation in parliament that would have lead to a different outcome - and yes, you can wring your hands about how FPTP makes for an unfair democracy - but they voted for that too when given the choice to switch to STV, recently.
The AV referendum was indeed lost, but that does not guarantee the correctness of your other claim, that "those complaining are a minority, or else they would have representation in parliament that would have lead to a different outcome".
The party in power in the UK is usually less than half of all votes cast.
And even when not, that it is representative democracy rather than referendums on literally every question means that voters have to collapse all the various topics they care about into one question of "which colour do I pick?" every couple of years — in an election there is no way to represent "I like Blue national defence, Red personal freedom, Green environmental issues, and Yellow on electoral reform", so looking at the debates listed on Wikipedia with the benefit of hindsight, even though I'm bi and the Blue party was homophobic, I might well have voted Blue due to this from the Red party:
"""On 24 May, Kinnock was interviewed by David Frost and claimed that Labour's alternative defence strategy in the event of a Soviet attack would be "using the resources you've got to make any occupation totally untenable".[citation needed] In a speech two days later Thatcher attacked Labour's defence policy as a programme for "defeat, surrender, occupation, and finally, prolonged guerrilla fighting ... I do not understand how anyone who aspires to Government can treat the defence of our country so lightly".[9]""" - https://en.wikipedia.org/wiki/1987_United_Kingdom_general_el...
In 1987, the Red party was seen as a shower of incompetence much like the Blue party is today.