The first cases made by Porper were done with a tapered cavity. The interiors are made of compressed foam, similar to what insulates a house or what is used for packaging. This foam can be deformed through pressure. Basically the foam is injected into a steel mold and it forms around steel bars and hardens. The material separating the cue from the raw foam is paper which has been flocked with synthetic fibers. Flocking is the process of using electrostatic to make the fibers adhere to a surface.
Three things are dangerous to a cue in a tapered cavity made from expanding foam. One is that the cavity can be misformed and have hollow spots which have brittle edges and those edges crumble with use and form small loose hard bits inside the cavity. Two is that the foam can seep through the seam of the paper liner and form a line of small hard beads. And three is that the flocking can wear off or even have hard spots on it where the plastic fibers have coalesced into knots.
Also flocked liners do not wick moisture away from the interior of the cavity. Any moisture present stays on the surface until it evaporates. So if your cue is not properly sealed then the latent moisture can go into your cue as it evaporates.
Eventually Porper went to a straight walled cavity and the parts can be inserted in either direction. This eliminates the problem with the cavity expanding due to pressure from the cue. The problems with the liner and the beading remain however with all types of these foam core style cases.
Tapered cavity cases are rare today as most manufacturers have gone to the straight walled no-taper style. We use padding to give the user the snug fit that a tapered cavity provides and we cover that with a soft cloth that will not ever harm the finish of the cue.
As has been mentioned any case which does not provide adequate protection can result in the pin being adversely affected. We think it's still rare for a pin to be bent when in a tube case but we put generous amounts of EVA closed cell foam rubber in the case to insure that the user can literally throw their cue into it pin first if they wish and have no fear that the cue will be harmed.
Here is a blog post of ours which further explains our position on how a cue should be protected
http://forums.azbilliards.com/blog.php?b=255
In short, a foam core tapered cavity case is not great for your cue. A snug fitting padded interior that is properly made is great for your cue. Any case you purchase should allow the cues to go in either direction as you please and should properly protect them in either direction.