I don't recommend LetsRun to other runners because of the trolls. Many top runners avoid it for the same reason. Some posts are so uncivil that it's embarrassing to be associated with a forum that attracts such people.
The brojos have their own objectives for this business (LetsRun is a business) and I don't know what those spoken and unspoken objectives are. So instead of saying what they should do, let me say what I would do.
If I owned LetsRun, I would take aggressive steps to limit trolling. Here is what I would do.
1. Immediately limit posting to registered posters.
2. Immediately prevent newly registered posters from posting for 7 days.
3. Immediately limit new registration to Facebook or Google accounts. It would prevent trolls from creating a temporary email address to get around registration requirements. Handles could still be used instead of real names to provide a veil of anonymity for posters.
4. Grandfather in existing registered posters with a strict warning that if they violate the Terms and Conditions of registration, they WILL BE INDEFINITELY BANNED WITH NO WARNING.
5. A stronger warning against personal attacks would be added to the Terms and Conditions.
6. Posters making comments deemed "uncivil" about minors would be indefinitely banned with no warning.
7. I would add a clause in Terms and Conditions that posters who violate the Terms and Conditions have specifically given up any right to anonymity and that they authorize their names to be posted publicly on this website or any other website. (Attorneys would have to work out the wording of this.)
This might temporarily affect viewership and revenue, but after a temporary setback, it might attract many top runners back to LetsRun. Wouldn't it be great to have a discussion with coaches, Olympians, and top runners who knew that they could post without fear of anonymous trolls attacking them?
Even if it affected the bottom line, I would sleep better at night knowing that I was providing a quality service for the running community. Life isn't just about money.
Just do something, anything, instead of just claiming ignorance. By and large this website has passed off the culture/comments of the boards to posters but you allow/foster the behavior and need to take some responsibility. So many pro runners are very open about not liking and avoiding this place. Instead of attacking them, think about why they do it. Why won't a prominent pro come to the boards and do an AMA with us? Because they know it will go off the rails very quickly.