We get good results from parked pages for the most part. Like you, they make up most of our content traffic and conversions.
"This is the first time I have ever seen a forum post about how advertisers are loving the traffic and ROI they are receiving from Google Domain Ads (aka Parked Domain ads)," said Barry Schwartz.
So if it doesn't convert for you, bear in mind that you'll soon be able to opt out of AdSense for Domains, according to Google.
Forum discussion continues at Search Engine Watch Forums.