I'm playing a melee-focused paladin in Storm King's Thunder right now, and it does seem ... suboptimal at times. We're still only roughly in the middle (no spoilers please) but the encounters that have seemed big, high-stakes, and plot-significant so far have been against giants. My character is certainly not useless against giants (I've gotten some great results out of Command), but I'm the sole melee-focused character in a predominately ranged party (archer ranger, crossbow rogue, light cleric), and my character's personality is of gleeful atavistic battle-hunger kept marginally in check by his oath and convictions. He WANTS to charge into melee, but a 6th level paladin doing that against half a dozen frost giants is asking to become roadkill. I can sit back and spam Command and javelins, but in-character the PC would find it frustrating, and out-of-character a cleric or bard could do it better.