Although they are not flawless, I believe that Just Blaze and Kanye West are two beacons of light in the urban music production game right now. They are fresh, original (yes that's right), and mind-blowing when it comes to their sampling techniques.
Let's take one of your examples, the Diplomats "Built This City": there is a vocal sample of Starship's somewhat corny "We Built This City (On Rock N Roll)", but Just Blaze manipulates that sample into an anthem of pushing drugs in the streets ("we built this city on rock" - cocaine obviously) with original electric guitars, a thumping bassline, and severe drum kicks to nod your head and/or get crunk to.
Let's take another one of your examples, "Champions" from the "Paid in Full" soundtrack: indeed this is not Kanye's best production (check "Get By" by Talib Kweli among others), but he takes a break including a vocal sample by the incomparable Freddie Mercury, and places a skittering beat under it for the Roc to flow off of. This modernizes the Queen song for the streets and does not follow the conventional methods of sampling nowadays (just take a song that's been sampled a million times, and do it over again, just loop it).
Just Blaze and Kanye West are trendsetters, which is probably why you think R&B/urban music production is getting boring; there are so many clones you can hardly tell if its them or not (not unless you listen closely). They also acknowledge Bad Boy's producers of yore, the Hitmen and Nashiem Myrick, as well as Deric "D-Dot" Angelettie (of whom Kanye was a mentee); hey, a former Bad Boy himself gave them their first big breaks (look at the Harlem World CD credits). It is obvious that they have taken their lessons from other sampling producers, and built upon them to create their own sounds, as well as fool others with original beats and well-hidden sampled ones.
I implore you and others to listen to their catalogue of music; it does not all consist of continuous loops of the sample throughout a track, but rather a progression accompanied with a syncopation to assist the speaker in expressing him or herself. Their catalogue also does not only include "soul beats", but rather songs with samples from pop/rock songs of the past as well (obviously including the ones you mentioned). If you couldn't tell, these are two of my favorite producers of the moment, and I'm sure that they'll continue to grow and shine in the future...