We had the "ice storm of the century" here in eastern Ontario and southern Quebec in January 1998. Five plus years after the fact you can still see the evidence. If the owner decided to keep an obviously gravely injured tree, there was not much than could be done except remove all the broken branches, which left many trees looking like crap, all the centers gone etc. as you describe. Birches bent right over, and never restraightened, the small oaks outside my office fared a lot better, evergreens were the least affected. Maples were devastated and greatly affected the maple syrup output and still is lower; some bushes lost 60% of their trees entirely, and the remainder were damaged. Not much you can do except make the tree safe, (hopefully) encourage regeneration of the removed areas, and many of the cuts would be made in locations no arborist would dream of cutting but for the damage to the tree. At this point many are being removed because they did not come back as the owner expected, or are decaying or dying off despite professionial attention. Many have also been cabled in an attempt to hold them together. I describe some of the trees east of Montreal along Autoroute 10 as looking like clipped poodles, no branches or leaves left at all except for huge dense tufts of growth as the tree attempts to compensate for its lost crown. I am not an arborist but am just reporting what I have witnessed firsthand as resident and later a groundguy.