Just give people options, those want to use it can pick any wallpaper or background they want, those that dislike it can turn off the feature
same as Android; not everyone use fancy background or live wallpaper, but the option is there for those interested
why not 920 or 928?
at least with 1gig ram and better camera, it is more future proof than 720...in my country, 920 is very affordable, less than $500 no contract, where 720 is about $329