I would like to direct your attention to her Heroic Ability:
Medivac Dropship
Target a location for a Medivac transport. For up to 10 seconds before takeoff, allies can right-click to enter the Medivac
If Illidan is THAT MUCH of a threat she can choose to flee back to a safe location with that
She may also just give herself Armor and walk away and sometimes she’ll actually succeed
The grenade isn’t mostly for saving herself but it can be used to save her ALLIES who are in danger
Like a Butcher who just finished his charge or has used his silence heroic ability on your ally
Morales firing a well-timed and detonated grenade will surely save her ally from death if their health isn’t extremely low
She doesn’t need any adjusting as her strengths make up for her inability to escape
She’s meant for a team who really needs healing and can protect her well
I don’t know which Brightwing you’ve been playing against
But when I find myself against one in most of my games
She teleports to her allies
Polymorphs her pursuers and gives them move speed while she ends up often getting away ALONG with her teammate
AND she now also has a CLEANSE that removes almost all disabling effects from her allies RIGHT FROM THE START!
She may not be the greatest healer in terms of numbers or the best at being constantly mobile due to her lack of a mount
But she makes up for it in other ways
I sincerely doubt people pick her ONLY because she’s cute