I've done *a lot* of crash-testing of my bike, especially this year (I've been racing my Tenere in the UK rally series).
The first thing that touches down is always the handlebars - mine aren't very straight any more, and I've bent a couple of pairs of handguards as well (although they've done their job and saved the levers). In most circumstances the bars keep the rest of the bike off the floor.
The next thing that touches down would be the grey panels on the side of the tank - ie the ones which the one you've posted don't actually cover. I have seen some which come all the way up and over those, but it's a bit silly - those panels are, as duibceK points out, there as crash protection for the tank. They do it quite well, it takes a lot to damage them to the point they need replacing, and they are quite cheap to replace (~£30 each in the UK).
It would be a very odd crash that caused damage in the area that those engine bars protect - and again, what they are actually protecting is 'sacrificial' plastic panels.
Those ones in the picture might be quite handy for mounting some extra bags on, or (as shown) mounting auxiliary lights, but I'm not sure they add much in terms of protection.
If I needed to buy some more, I'd be looking at the G-IT or other options which are similar to the Yamaha ones.