The whole 3rd party DVD thing is annoying, but I believe it has to do with MPEG licensing and such. I think Apple isn't bundling as complete of a a license as they could, to save cost. So iDVD won't do 3rd party burners but DVD Studio Pro does as it costs more and has better overall coverage of industry licenses. I could be very wrong about the license thing as well.
Toast is a nice tool though, so if you want to spend the cash it's worth getting, especially if you burn a lot and get into the whole drag n' drop thing that the Mac does well. You can still do a lot of advanced stuff with Apple's provided tools, even from command line in the Terminal.
And iDVD will let you author a disc to a disc image (another nice OS supported feature) that you can burn through other disc-image friendly applications that do support 3rd-party drives like Toast. No hacks needed.