Hmm...because I live in the upper midwest where there really are 4 well-defined seasons. Winter is pretty much the longest (from measurable snow to measurable snow it's generally a solid 5 months...this past Winter was easily a 6 month season. I was about ready to start shooting) and very VERY gray, here (Lake MI gives us near constant lake-effect clouds). Spring is wet and cool, Summer is sunny, warm and humid, Fall is cool and colorful. Our temperature spread from coldest to warmest is easily 100º.

I think if I lived in an area without snowfall or months of cloud cover (FL and the Southwest come to mind) that seasons might seem a bit less dramatically defined.