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maybe an easier fix is to detach the top & bottom in your modeler?..as in this obj exported from 3dsmax,it;s still one mesh but the top verts aren't attached to the middle ones
http://stefan-morrell.com/cyl_test3.obj
I dont think planar mapping a cylinder could be regarded as a fix,when it creates uv mapping you cant use.

it is an odd problem though,I tested myself & your right,with no uv mapping it loads without artefacts

However, you CAN use the mapping.  It's not the UVMap itself that matters if you're concerned about this "ripping" effect- it's the projection style, apparently.

All you have to do is Planar Project the map and then edit it using seams, pins, manipulation or whatever other tools you have available to move the vertices around to get a map that is useable with textures.  As long as it is still a planar projection, you should not have any of the "ripping" shadowy artifacts.  That is, if everything here is entirely correct and all of these experimental results prove valid.

I didn't manipulate the UVs at all in these projections.  I simply used the default map.  But, I COULD have easily manipulated them, created seams, unfolded them differently, manipulated the vertices and so forth.  I will be doing that in the next series of tests to see how they react and to see more specific effects regarding the artifact we see displayed in the above renders.