Ive known people who have been TKD practitioners and still do and these guys have made it work for them in a street fight. What TKD gives you is attributes for you to use as you so wish. having said that if an art is modified to be more practical in a street fight then it is no longer the art in its purest form.

TKD is a great workout and is great for fliexibility and will give you the ATTRIBUTES to use as you so wish in a bar brawl but dont for one second think your green belt plant form will assist you when some fellas fists start being an orchestra and want to play a symphony on your head.

Any martial art is only as good as the person who practises it. I will say though that boxing alone is not good for 99/100% of all street fights. A striking art alone is not enough. Ive known boxers who boxed for the royal navy. F****** good ones aswell get owned in bar fights by untrained street fighters who know the score. Boxers tend to fight like they do in the ring when in the street. To defend yourself well in a bar fight there is so much more needed than hard skills.Soft skills, awareness, knowing your surroundings, body language, attack cues etc etc are all needed. I dont doubt for one second that a boxer knows how to hit someone hard. If they get the first shot in pre-emptively then its pretty much over. Fists arent the only thing used in a bar brawl though. All tools become viable. head, knees (believe it or not a thai clinch in a street fight (in my experience) own lots of techniques.
A boxers muscle memory conditions them (as they have practised so much in sparring and competition) to keep form and box, punch with their fists. Fighting in the street and protecting yourself in a bar is so much more than that.

Training for self defence is an art on its own.