MPs are not really connected, but pixel size is, and in general, more MP means smaller pixels. A given amount of shake means a specific amount of movement in terms of arc-seconds. With smaller pixels, a given amount of movement covers more pixels on the sensor, which translates to more blur. So, smaller pixels means you need an even faster shutter speed to compensate for camera shake. 1/FL is a film rule. Even 1/1.6xFL is not enough on a high MP, small pixel sensor.
Thanks for that explanation neuro. I'd always noticed on my crop bodies the 1/1.6 photos were still a little blurry. I just always assumed that maybe I have more shaky hands than other photographers. But your explanation makes me feel better about me being more normal