D.E. should've definitely been an "addition vocal" for his contribution. Krizz has done more on tracks and not been given a feature in the past (as well as others).
snoop doggs verse was shit, but he does admit to writing it in a minute. i'm surprised tech was willing to pay for that, it was kinda like devin the dudes, but worse. they're both legends.
Apparently you haven't read any of the other threads. Plenty of comments on Snoops horrible verse, or the fact that Pornographic is just all around awful.
my theory, DE sent in 30 different verses and the only bar that Tech felt was worth the $5 DE charges for a guest appearance was shoehorned into the end of the track