Flap config for A330
 

Can someone in the know please explain to me why the Ldg Config has to be 3 if in Alternate or Direct Law?

Many thanks in advance.

Can't speak for the 330 but if it's like the 320 then roll control is always 'direct' in both Alternate and Direct law. Flap 3 landings are required as flap full degrades roll control in direct law. I don't know why, that's just what Airbus tell us.

When in 'Alternate Law' the 'Automatic Pitch Trim' is functioning, and pitch control is similar to 'Normal Law'. Therefore the idea is to configure the aircraft Flap3 and get the pitch attitude changes out of the way, then about 1000' agl lower the the gear, the 'Law' then reverts to 'Direct', pitch control is now direct stick to elevator with no autotrim, the machine now feels 'twitchy', but as no more config. changes are req'd. it's easier to control the machine down to the ground.
What Hand Solo says is also true, but it's the pitch that causes all the grief !!