The only benefit I see in getting an account is to get firmware.
The downside is getting spammed by them constantly about their specials (unsubscibe doesn't work so you have to write a mail filter) and getting preview books thrust on you that you may not want
You realize that Kobo isn't in the business of selling ereaders; it's in the business of selling books. The KT is just the vehicle you use to purchase and consume their product. I would guess that the margin on the KT is very low, and they are hoping you will purchase some books from them. When you look at it from that perspective, some of their design decisions make more sense.