This is to take account of the lower end of the range of the tolerances and VD of a nominal 230V/400 supply, if you notice they have also re-calculated the max Zs values (OCPD tables etc.) to take this into account too.
What gets me with this is that they already lowered these once to "harmonise" the 230/400 calcs (from 240/415), this new lowering probably makes some sense if you have a "real" 230/400 supply which we don't (we only changed the tolerance band) unless we are really lowering our supply voltage this time ?
More significantly, the commercial/industrial supervised person "get out clause" for RCDs has all but been removed, unless you are prepared to sign a RA to say otherwise, I cannot see many people wanting to sign that.
This will cause some problems with offices and the like.