Because they're human and can't always anticipate that someone will have a strong preference about a particular feature. Even with careful planning and testing you can't please all the people all the time.
Granted, it would be ideal if you could fully customize the address book view (and all views) but that wasn't possible in prior OS's either.
Originally Posted by dankarlinski
Double spacing where??
OP is referring to the fact that the address book also lists the contact's company. If your contacts are personal and don't have a company specified it looks like double spacing.