@Klumpen- it's not a mess
vanilla android was never meant to have the data partition (home) on a separate media. Just like angstrom did originally before it was fixed. I remember there being problems in the early days of the pandora where apps were still writing cache to nand. It's a similar problem.
Just give nvidia a chance to fix it and I'm sure they will.
The microsd vs full sd has been argued a bunch of times here so lets not go into that whole thing. I would have preferred user replaceable onboard storage or an additional sdcard slot (micro or full) but the current setup isn't bad, it's just not ideal. It's a matter of preference and what nvidia felt how much people would use those options and would it be worth the added cost of build and implement.