I always strip the bark for two main reasons. The foremost reason is that many species, such as birch and cherry, have bark that is very impervious to moisture transfer. This is why they used birch bark to make the early canoes. The moisture in a piece of birch will remain high enough with the bark on that it will slowly rot on the inside. They say this is "dry rot" but that is actually a misnomer. It was wet enough to rot and over time it eventually dries out, but by then any structural integrity is gone. The second reason I strip the bark is to remove any possible insect infestation. Many insect larvae are "bark borers" in their early lifecycle. They feed on the cambium layer of the inner bark and travel in that layer. By stripping the bark you remove them and their food. Also by stripping the bark it initiates rapid "seasoning" in the first couple weeks that reduces the moisture content dramitically. Any wood boring insect relies on this moisture and can't suvive in wood with a lower moisture content. Most of the time strip the bark with a drawknife whick leaves little facets and nick where the grain changes direction. It gives it a nice traditional charcter. Sometimes I will encounter a sapling that will peel easily without a drawknife which leaves a perfectly smooth surface, but it rare. It depends on specie, time of year, location where it was harvested as well as the health of the tree. After plucking a few hundred saplings it is still hard to predict.