The aspect ratios were added however it does not give real support for those ratio's since the field of view stays the same as with 16:9.
There is a way to make it all look the same size and that is by setting your field of view to 60, however then you see even less then with 1 monitor.
A game like DCS has proper support for 3 monitors and there you can really see the big difference.
This problem is still in the 1.3.5 dev build.
This is a screenshot with 3 monitors with a field of view of 60, this is to make everything look pretty much the same size on the monitors.
This is a screenshot of the same situation however on 1 monitor with 16:9 ratio.
Due to having a field of view of 90 you are now able to see more, with less monitors.
Here are another couple of screenshots showing a game with true widescreen support.
I find it rather strange that people claim this to be fixed when it has not been fixed, the aspect ratio's are wrong and the game does not spread the field of view proper on 3 monitors even with the new aspect ratio.