Malcolm X, Huey Newton, and Bobby Seale weren’t fighting for Civil Rights - they was fighting for Black Nationalism.
The central tenet of Black Nationalism is that peaceful coexistence between the races is impossible, and that blacks and whites must therefor live completely separate from each other and have nothing to do with each other. If that somehow doesn’t sound completely insane to you, take a look at how well that sort of thing is working between the Israelis and the Palestineans.
Please also note that all three men named above underwent drastic and sweeping changes of philosophy as time went by. The Black Panthers started out as Black Nationalists, then became Maoists, then cycled through a variety of other extreme leftist philosophies, and finally ended up as an anti-zionist movement. Talk about an identity crisis!
Malcolm X, of course, famously made the Hajj to Mecca and had a personal revelation, coming to realize that the so called “Nation of Islam” had little to do with actual Muslim faith, and consequently abandoning them and their cause of violence entirely - an act which shortly thereafter resulted in his assassination by the very people he once believed to be his closest family and staunchest allies.
One finds similar flaws in the efforts of Singh and Bose, but I feel I’ve made my point and need not go into further detail on their behalfs.
The very “palatability” you dismiss in the efforts of King and Gandhi is, in actual fact, the key to the success of their respective movements. When a minority is struggling for a cause, they very badly need the support of the majority population to achieve lasting change - and even the most sympathetic of potential outside allies become hesitant to support your cause if you resort to killing people.
Violence polarizes people. You may attract radical extremists to your cause with violence, but you repel moderates. You may believe acts of violence demonstrate the severity of the injustices being heaped upon you by others, but all it shows is that you are willing to stoop to their level and lower. You may believe violence will focus a discussion and force vital discourse, but all it does is muddy things, deflating your arguments and turning the vast majority of people against you.
People respond favorably to stoicism, not brutishness. When Gandhi went on his hunger strikes, they only had an effect because people admired and respected him - and not just his own supporters and fellow countrymen, but even his so called “enemies” and the people of the United Kingdom and the Western World.
But if instead, Gandhi had been known for being a violent, militant extremist? A hunger strike would be laughable - the world would be glad of him starving himself, feeling that one less violent maniac in the world would be the best possible outcome! A thorn in their side that removes itself from the equation? Who wouldn’t like that?
A person’s cause is only as strong as their willingness to suffer for it. Killing for a cause is easy. Dying for it, without striking back? Unimaginably harder, and of unimaginably greater effect.
If you take up arms for a cause, it has to be to engage in warfare - to achieve total and complete victory, and to forcibly impose your will to exact change, despite the wishes of the population at large. And even in ideal conditions, this comes with grave inherent costs - both in terms of human life, but also in terms of instability, unpredictability, and effective success.
Violent revolution condemns countless innocents to die and suffer for your cause without anyone asking their permission. There is almost never adequate justification to allow a person to decide such things morally.
Even beyond that concern, countless violent revolutions have succeeded only to make matters worse.
For every American Revolution in history, there are a dozen French Revolutions, explosions of passionate violence and destruction which achieve nothing but destabilizing regions for generations to come and paving the way for even worse abuses of power and popular sentiment. The Bourbon Kings were awful, no one contests that, but at least they didn’t plunge the whole of Europe into decades of constant warfare under a tyrannical madman like Napoleon!
And even the American Revolution nearly destroyed the colonies financially, crippling the economy for decades to come, and directly setting the stage for the War of 1812. Not to mention that it very nearly failed countless times over its duration, and was ultimately won not chiefly by strength of arms or popularity of cause, but by staggeringly unbelievable good luck and shocking incompetance on the British side of the equation.
So not only is violent revolution morally bankrupt in all but the rarest and most dire of situations, but it’s also very like to fail, and even more likely to backfire and make matters worse even when it “succeeds”.
No, I’m sorry, if you think violence is the answer, you are blinded by your rage and you betray any cause you seek to support.