/boot is on root partition by default
Using the alternative CD, the /boot directory is, by default, placed on the root filesystem instead of on it's own partition. The result is that data needed by GRUB can end up past cylinder 1024 on the drive which some systems will be unable to access at boot time.
This is very bad - the installer claims to have compelted successfully, but the system is left in an unbootable state.
Worse - it's theoretically possible that by some fluke the data will all end up below cylinder 1024 and the system will work - then at some point an update will break it by installing a new kernel beyond cyl 1024.
Whilest it may not always be possible to place a separate /boot partition at the start of the drive (e.g. people dual-booting probably can't), there isn't really anything to be lost by doing it where possible. At the very least, the installer should check whether the BIOS can handle reading from the end of the drive and warn that the system will be unbootable before partitioning.