No, it doesn't have to be. I just point out that on FAT32 SDCard, there are some known problems with the PND file system, and thoses problems doesn"t show up with Ext formated SDCard. But Packager should take care of that, not end user.
I guess Trezker as SDCard formated in Ext2 probably. And "Ext2" is enough, but you lose the ability to plug your SDCard in a Windows laptop for example.