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There was a discussion on this a lot of pages back. For a naturally aspirated, direct injected engine with modest aspirations (haha see what I did there?), they probably kept it simple. One of the things about direct injection that isn't immediately obvious appears to be the amount of flexibility you have when it comes to phasing cams. With a cam intended for high speed operation, at low rpm it has quite low volumetric efficiency and thus reduces pumping loss. Direct injection helps combustion stability in this case.
While the low end torque looks crappy, it's actually not bad considering how long the cam duration probably is. In the 2GR-FSE technical pdf, they describe how they can increase "internal EGR" (I think this means EGR that happens by virtue of valve timing trapping exhaust gas in the cylinder) quite a bit before things go bad with the direct injection system. The low end torque would probably be much worse without it (and it would probably fail emissions without some sort of variable intake lift or something).
Variable intake duration would really help on a turbo though, as it wouldn't waste compressed air when you're at part throttle, and help transient response. But seeing how electrically assisted superchargers, mild hybrid systems, (and logically, electric exhaust turbines would follow) are going to replace traditional FI eventually, it might be a pretty long way off before continuously variable intake duration would find its way to all engines. Not to mention, it works best with variable compression ratio.
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