Wouldn't a 50-year sentence be better than life imprisonment?

I understand that life imprisonment is the punishment just below the death penalty. However, since South Korea does not have a "life without parole" option, prisoners can be released on parole if they behave well toward prison officers or other inmates for 20 years. If we aren't going to carry out the death penalty and we aren't going to implement life without parole, wouldn't it be better to sentence them to the maximum limit of 50 years instead of life imprisonment? Under the Criminal Procedure Act, the upper limit for a fixed-term sentence is 30 years, but with aggravated punishment, it can go up to 50 years. Is parole also possible after 20 years for fixed-term sentences? If so, then that won't work either... If we aren't going to execute the death penalty or hand down death sentences, please at least implement life without parole. Even when death sentences are handed down, death row inmates are treated as unconvicted prisoners, meaning they are exempt from labor and just consume taxes while eating three meals a day alone in solitary confinement. I feel uneasy because heinous criminals like Jang Yoon-gi are still running rampant throughout society.