The instruction to drain 16 oz of oil is jus to prevent over filling. As I doubt you are close enough to exceed 7 quarts in your engine by adding just 16 oz, I wouldn't worry about it. Furthermore, it's not just 16 oz of oil in the filter that you lose when you remove the oil filter. You also lose a little oil right out of the nozzle. All together, that comes out to about 16 oz, so don't sweat it.

Why would you want to waste a new filter on dirty oil? You don't!!! And you aren't. By the time you need an oil change, your filter is beyond dirty, and practically clogged. When you put in a good engine flush like AMSOIL's, it will loosen SO much gunk, that what often ends up happening is the filter gets fuly clogged, and the by-pass valve opens up. So basically, all the gunk you've loosened up will now be circulating through your engine unfiltered, which is a REALLY bad thing to do, especially when you think about all those small oil passages.

I've heard some cases where lazy/cheap/unknowledgeable people with not so clean engines, used good flushes without changing their oil filter first, and causing more problems with their engines then had they not done anything at all.