no, you don't need to have a blank option, nor does the option select list "need" to have a blank selection, the first item in the select list can be one of the product option, so you could default to the color red.
The sample database is not necessarily designed for ease of use. It is designed for flexibility. the two do not go hand in hand.
Years ago, I worked in a bike shop, and we had a saying when looking at buying a bike:
"weight, strength, cost. pick two."
sort of the same thing applies here.