The most dominant reason to create a customized rescue image here (besides 
asigning a root passwd) is the missing sfdisk.  
 
Why? If you have to set up a complex sw raid 5 system with e.g. 10 partitions 
on each of 5 disks, it's a lot easier to create the partition layout once, and 
then copy it over. With sfdisk, it's as simple as running:  
for d in sd{b,c,d,e}; do sfdisk -d /dev/sda | sfdisk /dev/$d; done  
Easy, isn't it?  
  
If you do this with yast, you're going mad with creating those 50 partitions  
(at least I'm..), and I bet nobody get through this without doing some errors!  
Not to speak of the gain in time.  
  
In the rescue case, it's also preferable to be able to clone the partition  
layout quickly.