Open standard filesystems don't belong on a closed proprietary system.
Just a quickie:
Why not? I mean assuming no GPL-alike "thou must makest the whole product FOSS" stuff (and given that a GPL driver, which an Ext* filesystem would most certainly be enabled through, doesn't have these viral properties to the rest of the OS), why does an open-standard (GPL, LGPL, BSD, MIT, WTFPL, etc, etc, etc...) filesystem "not belong" on a proprietary OS?
My copy of ext2fs seems to be working just fine.