@bedrage
 
And you could also argue that Starlight was done better because she had actual relapses, whereas with Sunset, she essentially went through a 180, with no truly meaningful relapses.
 
Neither one of the two approaches are perfect, and in the end it falls to preference.

@Background Pony #80D8  
Eeyup.
 
Everyone acts like Starlight is a evil villain, when she’s not.

Uhm, you realize that unlike Cozy Glow, Starlight’s goal wasn’t destroying Equestria right? She only wanted to get revenge on Twilight and her friends, but she started to repent once she saw the consequences of her actions, being in a denial state first, then after Twilight opened her heart she accepted her help. Starlight wasn’t never outright evil (althought sometimes she says so herself). Cozy Glow was deliberately destroying Equestria’s magic and shown no resentment in doing it. She WAS evil. Regarding this thought i would point something: It pisses me off thought that writers realizes just now that really evil villains should be punished. I’m referring specifically to Chrysalis: after she was defeated in TWABA, they let her escape, when they should have done the same thing they did with Cozy Glow here. THAT was bad writing. TWABA was a total mess on multiple points anyway, at the time it made me VERY close to ragequitting the show, it’s still my most hated episode in the series. Luckily the show recovered since then to me, and with the next season being the final one, I can be reliefed that no other big messes that piss me off could happen.

@bedrage  
She don’t need no stinkin’ acceptance!

@AC97  
the problem here isnt that she faltered - its that she faltered and everyone accepted that.  
as we saw in rainbow rocks, nobody, except the humane 5, accepted sunset. and what sunset did was nowhere near the level of what starlight did. it took her an entire movie to show people that she changed her ways. had dhx given starlight some sort of punishment (again, what she did was way, WAY worse than what sunset did), and then, instead of cramming her redemption into a stupid montage at the end of s5’s finale, put it in s6 somewhere instead, then maybe she wouldve become a good character.  
but they didnt.

@AC97  
|| She ends up regretting her decisions… Blah blah blah. Decides to make amends. Yadda yadda. And then, BAM! She’s redeemed. ||

@TheMultiBrony21
 
||What the hell is there to redeem in her? She had friends, and chose of her own volition to be a psychopathic megalomaniac. ||

I’m sure there’s a 1:1 parallel between the two’s situation and context, yep.

All I could see when I looked at this picture was FILM LOGIC, instead of FIM LOGIC.
 
Sorry for interrupting the bigger discussion below with my sidebar there. xD
 
But basically my opinion feels like its summed up by this post:
 
@greaterlimits  

@AC97  
|| Until Hasbro decides to redeem her… Which they’ve done several times. ||

When it became apparent to Starlight that she was bringing ruin to Equestria, she faltered, and was able to be talked down from there.
 
Cozy Glow was fully aware that she was fucking Equestria up by draining its magic. What’s more? She has no remorse for any of this, and would never stop being a psychopath.

@UserAccount  
Unless they have her repent in Season 9.

Twilight couldn’t defeat Starlight with pure force, Starlight was open to reason and stopped on her own. Cozy on the other hand was not only defeated but showed no signs of remorse and even wanted to carry on doing what she was doing.
 
That’s not FIM logic, thats you being incapable of understanding what you saw so you can continue to hate on starlight.

If anypony repents of their evil, they’ll be allowed to go free. Cozy Glow never will, because she’s the most evilest cunt of all time!!!!

@TheMultiBrony21  
thats another good point - she and tirek were working together and she very clearly still has a plan after her inprisonment. it would be a big mistake on dhx’s part if season 9 did not open with the aftermath of this finale.

Actually… Cozy is pure evil… She literally refused friendship… Not to mention she WANTED to go to Tartarus.

the both of them put equestria in great risk. the difference here is that one is bad writing and the other is good writing.