First, I'll note for the record that I do not support many of the militaristic tactics employed by the black panthers. (From what I know the organization as a whole has done a lot of good things though, and members had a lot of diverse opinions on how to accomplish their goals). Regardless, I do think there whether something is "right" or not depends a lot on the situation, and who holds power (and how they wield that power) is an important variable to consider.
In an ideal world, any oppressed group would always be able to use Martin Luther King style tactics in order to accomplish their goals. In the case of American racism in the 1960s, obviously MLK pacifism worked wonders, and the reason it was effective was we already lived in a democracy that valued freedom and equality, with a free press. If MLK or Gandhi had attempted what they did in a dictatorship or a world where the culture placed no value on equality at all, they would have accomplished nothing. In that case, I'd consider militaristic tactics for an oppressed minority not only acceptable but necessary.
In the context of 1960s America, I do think some of the extremist elements of the Black Panthers were wrong, but I do think they would have been even more wrong if implemented, not by a minority struggling against injustice, but by people in power trying to maintain the status quo.
Now, with regards to "W.E.T." vs B.E.T, the reason a black television network is acceptable and a white television will draw criticism is the inherent mindsets involved in creating them. There's nothing inherently good or bad about "black" or "white" television. But BET was created as a response to the vast majority of programming being white centric. Black people didn't see themselves represented, so they went and made a network where they could represent themselves.
By contrast, what kind of white person would even WANT a network to themselves? They're already represented all over the place. The only people who would actually want to make it are either genuine white supremacists or people completely clueless about institutional racism and power imbalances. "They have a network so clearly we should ALSO have a network" ignores the reasoning behind BET in the first place. WET programming would either be identical to most other stations, or would be actually racist. Neither strikes me as a good reason to start a brand new station.
(Having said all that, I don't actually think BET is that great a network, but that's a whole 'nother story).