One thign I thought of is that it is not uncommon to 'dd' an entire
filesystem from one partition to another.
If we create a filesystem that is 'aligned' and we copy it to be 
'unalligned', we'd have a sudden performance drop for no immediatly
obvious reason. What was one write, would become a 2-sector read,
modify and 2-sector write. Especially when copying from one failing
drive to another with slightly different characteristics.

The idea isn't bad but I think it should be sold as a 4k sector
drive, with small print saying it can handle 512byte IO
instead of the other way around.