What is so important about the state of West Virginia? What would happen if it did not exist? why is it valuable?
Many have argued that the Civil War in these United States never answered the question of state secession, in other words, if states could voluntarily leave the Union. The Constitution in Article IV Section 3 states how states can join the United States, or how states may be re-formed, but nowhere does it state how a state may leave the United States. By virtue of the war, the Confederate States did in fact leave the United States, only to become reestablished after the war. When secession came, Virginia could hardly complain that its western counties were leaving; Virginia seceded, then West Virginia seceded from Virginia! West Virgina, by its very existence, argues that at least sections of states can leave states, if not states leaving the Union. However, a careful reading of the statute indicates that the Secession of West Virginia and its admittance into the Union was technically illegal by Constitutional standards, as Virginia never consented to it becoming a separate state (clearly the Founders never considered the case of part of a state actually becoming part of a whole other country.)
In the present day, West Virginia is home to vast coal reserves and a mining system that supplies much of the east coast with its energy needs. Most of the electric plants in that region are coal-fired.
One of the reasons why West Virginia seceded from the state and joined the Union was because the people and culture there are so different from the rest of Virginia. It's hill country, and the original settlers were Scots-Irish indentured servants who had given their seven years of work on a farm and settled there. They were too poor to own slaves, and weren't much interested in doing so anyway. They have developed a unique culture and history that sets them apart from the rest of the country.
Of course, to the people of West Virginia, the state is valuable as their home and they would be quite sad if it did not exist...
Historically, the main importance of the state of West Virginia is that it split off from the rest of Viriginia in 1861 as the Civil War was just starting. The people of that area of Virginia did not want to join the Confederacy so they split their part of the state off from the rest and it became a state of its own that was officially on the side of the Union.