Actually, "no value" does not mean 0.00 and NULL definitely does not mean 0.00.  NULL means unknown or no value.

I have worked with, and continue to work with, several databases with tables that have numeric fields where a NULL is necessary.  They are necessary because in these fields a 0 (zero) value means zero (production, amount, etc.).  This means we get a reading, but the reading is zero (a known value).  The NULL indicates that the value is unknown. For whatever reason, we did not get a value to populate with.  This could be due to equipment malfunction, communication failures, or any number of reasons.

In these cases we don't want to put a zero because that may mean we had zero production when, in fact, there is production, but for whatever reason we do not have that value at a particular point in time.

I agree that working with NULLs can cause problems but to simply say "never use them" is irresponsible.  Just like everything else, use them properly and know your system and data and you can work with the system you have.