Well, I can't say that Neil is better known in Europe/UK because I have no feel for his US profile, but I still wouldn't say he was well-known here. The Crowded House name remains known but so many years after their heyday I don't think they have that much pull. The last UK tour was much less extensive than previous ones and only focussed on a handful of medium sized venues. Neil's last UK tour was also relatively modest compared to previous ones. Quite to my utter amazement and embarrassment the final night of his last tour (in my hometown) failed to sell out by quite a distance.
I think the question is how much appetite is there among FM fans to see this new incarnation (at such high prices) and how much appetite is there among NF fans to see him play someone else's songs (for such a high price). I think the answer to the latter is "pretty small" and I could well understand why many FM fans are also passing the opportunity to see their band fronted by someone else.
It's perfectly normal for this to happen: Queen's audience fell after Freddie was replaced, INXS have struggled without Michael Hutchence. You take out one of the key reasons for people's fandom and people will lose interest. There must be very few examples of bands successfully changing leader/significant member and carrying on successfully. Off the top of my head I can think of Genesis, Marillion (and, ironically) Fleetwood Mac (but that was when Buckingham joined).