Obama executive appointments have led to a decrease in waiting on disability claims, and there's been a significant push to get homeless vets in permanent housing, which is significant because as with any homeless person, it's near impossible to find regular employment if you don't have a place to eat, sleep and WASH.
When it comes to reforming how VA medical services are delivered (where and by whom) that requires congressional budget appropriations, and even laws to alter the scope and purpose of the VA. We are looking at significant increases in patients. Much more than just medicare. While the Vietnam era guys are aging, we also have all the guys who've been through all the mult tours in Iraq and Afghan.
I'm not saying Obama's a great potus, but all in all, given that there's zero bipartisan cooperation in his final 4 years, imo he gets a passing grade on this. His grandfather is a vet, after all.