Even the best plates in the world require someone competent enough to hit them. That's a Captain Obvious statement, but we lost a good kid in 2007 to a "sniper" who threaded a bullet between the front and side SAPI plates, and hit the heart.
The great plate and AP bullet race was on in the early 2000s. We came out with plates that would stop 7.62x39 AP, and our boys started getting shot with 7.62x54. We came out with those hybrid gel plates to stop 7.62x54, and our boys started getting shot with 7.62x54 AP. After we came out with the ESAPI, I don't remember getting any more updates as long as I was issued plates. I did go from MTVRs back to plate carriers though. That was a relief.
In a decade we went from Vietnam-era flak jackets, to MTVRs with ESAPIs. Along with that came side plates, dick guards, throat guards, and the Army even had their poor bastards wearing those shoulder guards for a while. That was a pretty swift advancement in armor. **Admittedly, I don't keep up with what the current warfighters are being issued, so if there are more advancements please inform me.
Today, one could probably cheap out and get AR500 plates with an anti-spalling coating. Ceramic plates are still the bees' knees AFAIK.
As long as your plate can absorb 3-4 rounds of your common military cartridges (up to AP) and not frag your throat too much, I think it is doing everything one could ever hope for. Past that and you might want to reconsider your tactics...because they suck.
Innovation should be made IRT weight if you asked my (worthless) opinion. If you can get the above-mentioned level of protection and shave a pound or two... then you are moving in the right direction.
It'll take another major war to see real Innovation again though.