Why Customers prefer Muti-Demos over Well Designed one demo?

I’ve noticed that customers prefer to buy those themes which have multiple demos (irrespective of the fact, most of those demos are sub-standard and might not get approved standalone) over themes which have well designed one demo? Preferring multiple demos over good quality is strange behavior considering they are expected to use only one demo on the final site and they have to repurchase the theme license if they want to use any other demo for another site.

What do you think what is the reason behind this behavior of customers?

Hi just to give you some feedback I think I look for themes which are easily customisable to my needs. So even though a theme may look great it might look only good in that particular design. On the other hand a theme might have some lots of variations which means it is easier to see how it can be customised. Just my opinion.