Weight reduction is the reason mostly mentioned in order to explain why cuirassiers neglected their cuisses in the 16th century.

Are there any other benefits in terms of manoeuvrability you get if you leave the lower leg defence away? How much weight would you save?

When fighting infantry in melee I suppose this area is still quite vulnerable even if protected by leather boots. Was it really worth to create this open spot? The other body areas on the contrary have been pretty much enclosed with metal not leaving a tiniest hole (except some slits for vision and breathing). I even saw on some armours that the bend of the ellbow were covered with flexible lames.

Helge,

There are several reasons why greaves were omitted. Yes, weight was probably one of them. But it wasn't just in the late 16th and early 17th century that greaves were done away with. If you look at the drawings of Dürer and others, you will see that they quite often show 15th century mounted knights without greaves on. And as anybody who rides with armour will tell you , you have much better control of the horse with your legs without greaves. They ( the greaves ), are also amongst the most difficult pieces to make and therefore expensive. By the early 17th century armour was beginning to be somewhat symbolic anyway, and as a thick leather boot was as good a protection, if not better, than armour plate, the greaves went.
With the use of more and more powerful firearms, armour was becoming obsolete, and more and more professional soldiers were choosing not to wear the cumbersome armour that was being made.

Regards,

Russ