Unlike BitCoin or cash payments, Taler ensures that governments can easily track their citizen's income and thus collect sales, value-added or income taxes. Taler is thus a currency for the mainstream economy, and not the black market.
Sounds pretty useless to me then. I would think, as technologists, we would adhere to a mindset of "we can do better". That is, we can do better than basing our society on a State apparatus that is rooted in the use of violence (or threat, implied or otherwise) of violence, to coerce people into following its dictates. Taxation is damage that we should be creating ways to route around, not something we should be building tools to support.