The only way to fix Ling in its current state is to give it a true endgame and with that, more ways to obtain "evolution points" without being forced to kill every god damn person you see.
Im gonna bring up the two type of lings that currently exist in the codebases, which is the progression ling and the static ling
Progression ling has many flaws, mainly the need to constantly being forced to kill new victims for a limited award. However powerspikes like the horror form and stun sting feel sudden and out of place but also stupidly out of reach. The Horror thing is currently my most hated upgrade due to the Ling being little less than a traitor with the objective to murderize the entire station because it simply exists to feed.
The horror form takes 5 victim to obtain, considering you didnt spend your 5 starting evo points on any upgrades. When you do a ling without spending any upgrade points then you are the worst antag there is. You are not only forced to work with your departments tools in order to murder 5 people without being spotted, but you're working towards a powerspike which is currently a round ending evolution as the station doesnt have the firepower to remove this threat easily, the only weapon coming close to that being the shotgun.
Static ling has another set of flaws that is hidden under the basic concept of objectives.
Static ling starts with every power open for it, however it only has a limited amount of slots, so it has to wisely choose which powers to take in order to complete the objectives given to it, the player is asked to find the best possible way to complete whatever task he was given, without being forced to work for the tools. This presents another problem however, as there is no sense of progression and as such, you're never stronger or weaker much like many other antags. This lack of progression is very noteable on TG, as very few antags have a true sense of progression, aside from Blob, Cult and Clock Cult.
On Aurora the ling has no real role aside from being stupidly annoying for secruity to deal with and stupidly boring for players to interact with. While roleplay is of course there, its mostly you begging for mercy as a being that only craves to devour eats you. Thats it. While of course you can argue that a ling is able to do some RP, it simply doesnt fit the antag, as they're again, simply there to feed on the crew and not to hear them tell you a 20 hour long backstory while thinking if its truely the right thing to suck their bodily fluids out.
I myself believe that adding a true progression system would be the best, which also forces more ways to obtain whatever resource you require without being forced to kill every guy you see.