Or Grom could have swallowed his pride, actually talked to the night elves, tell them their situation and only take what they needed instead of trying to strip mine all of Ashenvale.
The same could probably have been said of the Bael Modan. They could have probably tried to negociate but it seemed like neither side wanted it and now everyone involved in Bael Modan are dead.
At this point nothing can be done about Bael, something could still be done about Ashenvale, unless both sides want a repeat of the Fourth War and we can all be back here in a decade or so.