Is it just me, or is kinda unfair that witchdoctors and musketeers get less than half the amount of passives that buccaneers get? Elusive three quick draw 2 and double tap 2 aren't exactly special compared to vengeance strike and swashbucklers riposte. I have thought about this topic for a decent amount of time (about 3 months) and think a buff is necessary.

I think that it's fair. Each faction have their own strengths and weaknesses.

Witchdoctor

Pros: Excel at long-ranged combat and minion summoning as well. They can also charm a foe & make the enemy fight for them [the Witchdoctor] for 1 round.
Cons: Low health and dodge, with a staff it's a 75% chance to hit each target, which can increase the chance of one fizzling on their basic attacks. Witch Hunter decreases their damage output for a round when triggered and they have 0 base armor as well.

Musketeer

Pros: Same as WD minus the minion summoning of course. They also have high base accuracy as well.
Cons: Same as WD minus the staff weapon.

Buccaneer

Pros: Excel at melee combat & have high health+armor to back it up too.
Cons: 0 base resistance, Reckless Frenzy drains health with every successful hit, no long-ranged powers.

Swashbuckler

Pros: High base dodge and accuracy, have high base movement, can poison and bleed targets into submission & can go hidden as both an offensive & a defensive maneuver as well.
Cons: 0 base resistance, short-ranged distance attack via hurl/throw knives, hidden doesn't protect against aoe attacks.

Privateer

Pros: Jack-of-all-trades when it comes to the type of combat they prefer, have multiple offensive/defensive buffs, excel in team-fights and have the highest number of heals in the game as well. They also get the most companions in the game compared to the other factions of the game as well.
Cons: Heavily reliant on companions & allies/teammates to do their fighting for them and are not very good by themselves in a 1v1 either to boot.