PAL games has nothing to do with this being HDMI only. This thing isn't outputting anything at its native video standard so even if there was such a thing as PAL signals being unable to be transmitted through some styles of cables (which I don't believe to be the case), it could simply convert it.
It's HDMI only because that's all it needs. The primary appeal of this thing is its HDTV capabilities and since HDMI is standard, it simply doesn't need anything else.