I've built Yggdrasil lvl9 on Beta just some weeks ago, so I remember, how hard it was to finish Viking settlements even without cost of roads. More of that - I was not able to finish it in time last 5 or 6 rounds, so no extra rewards for last months. Every viking settlement was long enough and boring even with free roads. And yes, it is necessary to rebuild settlement almost every day. And every round of my last 5-6 I needed copper coins very much, there always, always was a lack of them until the last 2 quests in line. What it will be when roads will costs such a great amount of copper coins? 2 months to finish Viking settlement? Is it supposed to be a game or a torture?
As for Japanesse settlement - it's more easy compared to Vikings'. Playing it gives me fun - and that's what any game supposed to be. What it will be with roads' cost - I don't know. Maybe it would still be manageable.