Didn't know about the Van thing. I'm just a french guy living in Brussels and I don't speak any flemish/dutch, unfortunately. But I mean, it's quite natural and self-evident to shorten common prefixes, so for De and Du, "D." would still make a lot of sense (even it it's still two characters and there isn't much gain of space). For a name like "Kosciusko Morizet", though, it's a lot less natural. However it's still very practical because "K. Morizet" immediately registers as "Kosciusko Morizet" in my brain if I previously knew the name. On the other hand, "Kosc..." might require quite a bit more time for me to realize who we're talking about.
But since you're the expert..
PS to developers: Don't be afraid to revert back to the original system if you feel that it's the way to go. I'm sure most people haven't noticed the change yet anyway.
"Air is beautiful, yet you cannot see it. It's soft, yet you cannot touch it. Air is a little like my brain." - Jean-Claude Van Damme