The main reason for adding applications to the ROM is space. Anything that's been installed in the OS ROM isn't taking up space in base storage. The hard reset situation is an added bonus.
Truth be told, the higher the number of commercial applications you have, the better off you are rolling your own, particularly since you can then do neat little things like adding in your registration keys in the proper place in the registry. It's also a pretty easy thing to do, and it lets you have everything just the way you want it (rather than needing to deal with somebody else's preferences, particularly when it comes to applications).