Every time I install RedHat it's the same thing. I can't use the "standard" installs because I want to set up a Windows dual boot. It sure would be nice if anaconda would, during a "standard" install, let me enter a number of megabytes to leave untouched. Better yet, have it make a DOS partition of a particular size. I think it's common for first time RedHat users to want dual boot capability.
Actually, I would think that the majority of first time Red Hat users that want to dual boot already have Windows on there machine. Thus, their DOS partition already exists. Plus, I think this would really frustrate users that don't have Windows on their machines at all. This would basically allocate disk space for an operating system that they don't have.
It would be a OPTION, and a simple one at that: Disk space to reserve. To use the entire disk for RedHat, enter 0. To save some space for later use, enter a number of megabytes [ 0 ] [ OK] [SKIP]
You already have the option of partitioning the disk manually with Disk Druid. You can reserve all the space you want to. Automatic partitioning, by definition, is designed to be automatic. If you want options, Disk Druid is the way to go.
Then you're right back to the complexity of figuring out which partitions to set up, what size swap to use, if you should creat a boot partition. Just telling the thing "ignore the partition that's already there" or "leave me xxxx megabytes to manually partition" would make this worry free.