And I assume that you warned the Fighter and the Paladin to rehaft their polearms accordingly before they entered the dungeon so they can keep that extra d4, but conveniently neglected to inform the Barbarian? Or, you know, the polearm user could choke up on the haft before swinging it round?
This entire rant feels like tone trope policing of the highest order. It's none of your business to try and micromanage every aspect of how your players envision and build their characters so long as they're staying within agreed-upon material. I could understand your objections if you were running headlong into the PAM-Sentinel combo -- maybe not be sympathetic to, but at least understand -- but as it reads it feels like that you're trying to put Barbarians in a tiny suffocating genre box in a game system that encourages finding alternate expressions of mechanics.
Also the pike isn't eligible for Polearm Master for whatever reason. Only the glaive and the halberd are.
I was just referring to the pike, which
@doctorbadwolf considered to be an archetypical barbarian weapon but he cleared that up to be a long spear instead.
I house rule spear anyway to be a 1d8 two handed 5ft reach weapon whith which you can apply PM in my games, so, no in a normal dungeon corridor you could twirl around with it. And to further anger your critizism on my trope faible, in a game where barbarians would play an important rule, aka be egligable for PC class there might not be any other polearm available, or only savage versions of glaives or tetsubos or such.
And tbh I am perfectly fine with ruling that sometimes a dungeon corridor might be to narrow to use long weapons, so the (wo)man upfront could perfectly use his spear but not twirl it in this case, same with a halberd, Also the one in second position could use a reach weapon but also only to thrust.
I sometimes want tropes and sometimes not so much, but I hate ridiculous things like a gnome or Halfling wielding a weapon not intended for their body size. It breaks my make believe and I do not enjoy it.
And if some wants to play powergaming I am ok with it, and he can come up with whatever build he likes, there will be a suitable monster to counter it. And so I tend to agree with the players upfront, and if there is something missing I either try to build it in, build it in with a twist, or suggest something different.
More often than not my narrow selection is more than enough for my group, some races or classes I like to see in play are not chosen by them many of them are into playing humans e.g. And I also discuss the predominant playstyle and pillar if there is one. And that might be RP or Powergaming or investigation, but I give recommendations upfront e.g. either minmax a bit or put some points into cha for social skillchecks come often or whatever.
I do not care about PAM Sentinel combos, because if someone plays a powerhouse in my games it is because I want to dm a game where power house is a possible character build and plan accordingly (e.g. use more spells or mobs which can compensate a bit for the strength of a certain build)