Portability (being able to take a 100 books on a trip instead of just a few or getting rid of the weight)
I like to travel light. Especially when going skiing (we usually go by train) or biking (obvious reasons...). And on holidays I can devourer books...
Gadget love (you love gadgets and buy any new gadgets that come to market regardless of usefullness)
This was the reason I bought my Promedia, BeBook Mini, JE100 and Sony 650... Actually, it was part of the reason I bought all my readers, but the older ones (my Ebookman and PDA's) I bought mostly for the above stated reason.
You were already reading books on your computer and this is easier to carry around and read in bed
I started on my PC, then moved to the Franklin Ebookman and that was the beginning of the end
Your e-reader is more comfortable to hold in your hands then books are
You try to hold a hardcover for a few hours! Or try to hold open a MMP for a few hours!
You love anything shiny, just like a crow
The Sony 650 just looks awesome....
It's easier to read in the dark (because you have an LCD-based device or an e-paper based one with built-in lighting)
I have one for all situations, including sun-light reading and lightless reading