i'll try to keep this short ahahah..
ok back to the football field of buckets.
let's say the size of the football field is 100m x 100m, and the
diameter of each bucket on the field is 1mx1m. so there's 10000
buckets
to fit more megapixels in the same area u would have to make your
buckets smaller, say maybe 0.5mx0.5m, and u'll need 40000 buckets.
and that's exactly wat they do to make more megapixels.
there comes a point where no matter HOW SMALL ur buckets are, u
still won't capture more water.
another is that, with any given AREA (of foot ball field) there's
only so much water u can catch. if u wanna catch more water, it's
better to increase ur AREA, hence, get a bigger field. u'll be sure
to catch more water (detail) that way.
in camera terms, just use a bigger sensor (CCD/CMOS)
this is by far one of the biggest difference between dSLR and
digicams.
digicam sensors are half your thumbnail. dSLR sensors are the size
of the upper joint of your whole thumb. 
