I want the best bang for the buck and most new pre/pros with HDMI are pricey. That said, I see the Emotiva DMR-1 receiver ($999 on sale) is $300 less than their DMC-1 pre/pro. Interestingly enough, after inspection of the images on Emotiva's website, the receiver seems to be internally identical to the pre/pro ($1299), except for the built-in amplification and minor layout differences. Also, the balanced outputs on the pre/pro are replaced by speaker outs on the receiver.
Anyway... it's just perfomance vs price. Also, separates allow individual upgrades vs replacing the entire all-in-one unit. The fact is the manufacturers "have it out for us". They want us to keep buying their new stuff, right? Why would they make products that never need replacement?