It is probably rather easy to optimize the driver profile for maximizing 3DMark11 scores (or any canned demo for that matter).
Because I'm testing Intel drivers regularly I can say there never were really untypically improvements in 3dmark Vantage or 3dmark11. When Intel added driver improvements primarily games improved not 3dmark. From launch driver to the current 15.31 3dmark11 and Vantage improved only by 5% on Ivy Bridge. This isn't that special, there are lots of games which improved much more. Of course Intel suffered (or still suffer) from a couple of performance issues in games. The biggest issue was their annoying low clock bug with 15.26 and 15.28 Ivy bridge drivers. I'm glad they solved this in 15.31. In several games with this low clock issue I saw roughly a doubling in performance.
For 4600M is so because of the lower GPU clock and memory BW bottleneck. It's a moot point since Richland is what will be competing against HD4600 and not Trinity. Also price will play major role so if you are to have more fps in games and less in 3dmark(with Richland) with noticeably lower price for laptop, what will you choose?
Trinity isn't cheaper, I guess same applies to Richland.