While I think it's too late for this to see widespread use, I think this is a piece of code that should be highly encouraged to be used. It may be worth a followup patch to actually use this in node.module, where a GREAT benefit could be had.
The benefit? If the schema is modified, NO code changes are necessary to change what data is loaded/saved from that object. The other benefit, really, is that it is guaranteed to be type safe and some of the queries that write data into tables can be quite long if there are a lot of fields; this reduces that code quite a bit since we now have a list of all fields available, and their type.
It also introduces a flag to schema API: "serialize". Simply, it makes the api smart enough to serialize fields prior to writing / after reading.