Thanks for your reply, Lightning UK.
Well, first, for general use, it may be useful to have ImgBurn as a bulk eraser if you need to blank out a bunch of rewritables without burning images onto them. You may wish to do this because you prefer to use a different program for mastering CD's, or for security reasons, say for erasing backups of sensitive data.
If you want my specific use case, it is a little complicated. I burn mp3 CD-RW's using iTunes, which then play in my DVD player, which can play mp3's. That way, I can listen to a random, custom mix of music on my nice stereo system instead of my PC speakers. This may sound a little far-fetched, but is actually a decent way to get a mix of music onto a big stereo without connecting a computer to it. It has totally changed the way I listen to music.
After I'm done, I must manually erase the CD before putting new music onto it, because the good folks at Apple have not built this functionality into iTunes. Since iTunes does a magnificent job of creating dynamically-generated playlists and burning them to CD, I'd prefer to keep this software in spite of its minor limitations.
In other words, I use ImgBurn to only erase CD's because I prefer to use another program for mastering blank ones. (In this scenario, anyway. I also use ImgBurn for other things.)
I understand that this is a limited use case, and I want you to know that whether or not you can help me with this, I do appreciate your time and effort in creating an impressive and well-written piece of software.