I'm actually surprised most people think friesians cross well and pass on their look. I think its more that people are finding these lovely stallions that crossed well but if you search for friesian crosses on dreamhorse.com etc... they just don't look very friesian-y to me.
I think it depends on the individuals being bred. Our stud passes on a distinct look but many others do not... that's why I've never cared much for cross breeding them. You have to really know what you're doing.
When I was younger we had two friesian/paint crosses and they were lovely but you wouldn't know they were from friesians.