Earth, Animals, Agriculture: Clearcut Logging, for why?

Explain to me, someone, why this is still a legal practice?

I was under the impression that studies have shown clearcut logging to be detrimental to the environment for reasons from the obvious immediate habitat destruction and soil erosion, to *future* habitat loss caused by destruction of old-growth forest. Have you ever walked in an old growth forest? Noticed the space between the trees, the shrubs, ferns, and other low-lying greenery that exists in the patchy sunlight?

You don't get that in commercial second-growth forest. Some forest management plans only call for leaving a certain number of 'unusable' trees standing to reseed the forest naturally. Perhaps a better, if slower choice than replanting, I haven't found any studies on that particular subject. As for companies who replant, I'm sure they think they're doing a wonderful thing, even replanting two trees for every tree they chopped down, but has it occurred to them why there was only one tree there to begin with? There simply isn't enough room, enough sunlight and soil and water in that one spot to support anything more than that one tree. No undergrowth, not even shade tolerant trees. Commercially replanted forest is only good for one thing: More logging.
Now, mind you I HAVE studied both sides of this issue, and I like to think my own natural leaning (and my cynicism) are not entirely at fault for my personal opinion. If you read the stuff the logging industry puts out, they lead you to believe that they can A) get the logging done without causing any damage to peripheral environments, such as the trees they AREN'T chopping down, the soil, the undergrowth, the animals, the streams, and B) clearcut logging is good for the forest because it opens up areas for diverse animal life to roam.
Read the information on this webpage by a Canadian company working to shift the demand for paper products to renewable resources, rather than old-growth logging: Protecting Ancient Forests and read this article on clearcutting in Wikipedia: Facts about Clearfelling, then look at the world around you and tell me who YOU believe.