So what you are saying is that you are already using a music database program. It just doesn't have as many features as some. Hold in mind that most of these programs {including iTunes if you set it up that way} will let you dump your music into any set of folders you want. All the work is done in a database that references the actual files.
I could just copy paste the top level iTunes music folder too (if it would fit). I find syncing to be less trouble and faster.
The smart playlist looks just like a playlist, and you use it just like a playlist, to play a subset of the songs in your collection. You can do this manually by sorting and selecting, of course. Heck, you could do that for normal playlists, painful as it would be. The idea is to set up common sorts and selections so that you don't have to do it over every time you want to listen to that group of songs. It is only useful if you have groups of songs that you listen to often, you add songs to often, and can be grouped by some attribute. Some people don't and some people do.
I'm not trying to convince you that you need to do this. Only that there is a case for it and that others can and do find uses for these features. I have little use for many of the features available on my phone and computer, but I have no trouble imagining the uses they could be put to.
