This is on the todo list already. Not yet implemented because libburn does not include read support. There are ways around that, of course, but they'd require more time to implement.
First, here are my 2 cents. Now, I hate that feature, never use it, it's a big waste of time. The last time I used it was on Brasero and I ran away from it. I burned an ISO image which was finally checked, said to be fine, two times and the disc was unreadable. Switched back to Xfburn and everything was fine.
So please, make this easy to activate/deactivate :)
I agree that it needs to able to be turned on and off. Most programs by default do not do this with audio CD's, but do with Data compositions. Personally, I have to have this when I burn ISO's, it saves much embarrassment when testing distributions.
However, not having the feature at all makes this program unfit for use for me and my clients. I am NOT adding the headache of dealing with bad disks to all my other tech support issues. So for now, I like the many others like me are stuck loading either the entire gnome library or the kde library into memory if I want to do this from GUI. It makes XFCE look very amateurish and is one of the reasons I can not get people to switch.