Too bad we can't trick windows to use ramdisk HDD as Ram, that the "doublebuffering" Ram and Ramdisk is not needed anymore.
This practice sounds very wrong. Do you mean the practice of someone putting their Windows Virtual Memory on a RAM drive? Unless you have >4Gb RAM and running a 32 bit OS which can't make use of the extra RAM, this practice is pretty dumb.

By all means, put the temporary folders/files and FFXIV on the ram disk though, just not the virtual swap file.

The very annoying thing is, that the memory leakages of this game arnt solved with it, nor setting an PAE bit for all FFXIV exe. This game doesnt use more than 2 Gib of Ram.
You just contradicted yourself there. If it doesn't ever go above a certain amount of RAM, it by definition doesn't have a leak. It's just plain bad at making good use of available system resources.

Oh and PAE bit doesn't mean anything on x64 Windows.