That is an important question, isn't it? I think the way we answer reveals much about what we think of marriage. I know most people, especially "these days," would say that the practical and sensible thing to do would be to get joint accounts.
After all, in the event of a divorce or separation we wouldn't want to have any confusion about "who brought what" to the marriage financially, would we? Perhaps separate accounts are very logical, sensible, and practical.
The only thing is I think separate accounts are a terrible message to send each other at the start of a marriage. And yes, I know how high the divorce rate is these days, in the U.S. and I suppose its rising elsewhere.
Still, I am a romantic I guess. If you can't trust your spouse (aside from your mother and other blood family) who can you trust? It just seems to me that two people should not enter into marriage with a eye, simultaneously, on an escape hatch -- which joint accounts are, in a way.... to my way of thinking at least.