I can see your point of view, and I share it in some respects. In many cases people were just careless or knew that there credit record was such that they accepted whatever rate, including PPI charge, a lender would give. In some cases people did want PPI but because it turned out the circumstances they wanted to be covered for never arose (Sickness, redundancy etc) they may now be claiming it back (whereas they would I am sure have taken the benefit if something like illness/had occured).
But there was misselling in the sense that advisers sold policies that were not suitable- eg with redundancy benefits that couldn't apply because the person was self-employed. I think in some cases it wasn't explained either and people didn't realise they'd be charged it until after the payments came out of their account. Okay, you could argue they should have read the small print, but let's face it, many of us don't. It is also argued some were wrongly told they had to have it (although I'm not sure why they didn't shop around).