Personally, I'd rather have the stickers - but only for tradition's sake.
When I was a kid, I'd peel off the stickers - more often then not - and placed them on book covers, the inside of my school desk, my bike, etc..
As a teacher, I hand out WP to my 9 - 11 year old students as incentives, and strangely ( at least to me ) they do not peel the stickers off. They say it ruins them and makes them worth less money. Instead, they store them in binders along with their baseball and Pokemeon cards. Ah, what a generation of savvy kids!
So my guess would be that if nobody is now bothering to peel off the stickers - myself, now as a collector, included - why bother to add to the production cost by having die-cut stickers? I think, for the most part, that stickers really now only appeal to the traditionalists.