I think the bigger story remains to be told. It is not, IMO, the enormous loss he's written off - hell, I wouldn't mind having the gains to write off a loss of my own I'm still carrying over. Trump can call "not paying taxes" smart, but this revelation only suggests that he's just as good at losing money, perhaps better.
What would be far more telling is the bigger picture of how much money he has actually made and how much in taxes he has actually paid, and what charitable contributions has he actually made.
The apparent fact that a quarter million dollars minimum has been funneled through the "Trump Foundation" - probably illegally - may still be the bigger story than just "he's paid no taxes." If he didn't have to pay personal income taxes because he directed funds to his foundation that should have been declared as income on his personal tax filings, well, dat's not good.