I think with a longterm view when PR was introduced it was a good indicator of how long you'd stay well ranked for targeted keywords. Higher PR definitely gave a consistency to results ime.
That's when PR started getting 'sold' and it was devalued to the nothing it is today. A few of my sites saw a drop too, thankfully it no longer concerns me although it's pretty sad to lose a PR6 when it meant so much for so long
Getting #1 with a PR0 for a worthwhile 3+ keyphrase is extremely doable now which helps with new-site-motivation.