I own HALion 4 and Kontakt, but I think that Nuendo and Cubase deserve a complete sampler, maybe not as good or as complete as HALion is, but one good enough to support your everyday work.
Unless the sampler can do things that Kontakt can’t, I wouldn’t be interested. For example even though EXS is a load of old tripe, it has the ability for rendering in the background, which could be very handy for some things. If not, why would I want another piece of possibly buggy, ugly and badly designed cr*p? I already have Kontakt for that.
I understand that you and me don’t need another sampler, but I think that having a good sampler as standard is good for the platform.