The "(sensors with) smaller pixels are bad" line is a myth, and I'm disappointed to see it spread here. There are densely packed sensors, and there are physically large sensors - both are good things.
Of course, if you had the exact same pixel count, larger pixels are naturally better, but this is not the question facing sensor makers. The "small pixels" line is harmful because it leads people to think that small pixels are naturally compared to large pixels - almost nobody does this, because it would mean viewing pixels off different size sensors at the same size. With a few exceptions, people compare the full images at the same size - where total sensor size is much more important.
DP Review's Richard Butler took a look at this question last year, with some extra math details on page 2 of the article "The effect of pixel size on noise."