I agree, the insistence on allowing players to do stuff like that kinda reeks of the bathos and irony-poisoning that is plaguing mainstream media, where you cannot even try to do a serious scene without someone laughing at you for taking it seriously. Not everyone wants to turn every campaign into MCU, trying to do so like that sends clear message there is tonal dissonance between player and the GM and the thing I would probably do is either shut such gross behavior down, point to our lines and veils or pause the game entierly to talk with the player.
In my experience that kind of bathos is what D&D does best:
On Bathos
It is just plain easier to run bathos than pathos in D&D and faaaaaaaaaaaaaaar easier to run D&D with a Swords and Sorcery tone than an Epic Fantasy tone.
I've always found that if you want more pathos and narrative structure in a game, it's far easier to do that with an Indie/Story game in which narrative structure and pathos are build directly into the rules. That sort of thing is hard to cultivate in D&D with how incredibly random it can be and requires the players and party to stay focused and put in the effort. On the other hand if you want the tone of the Dying Earth books by Jack Vance you can get them by just pouring some beer, rolling some dice, and letting loose even if none of the players have ever heard of Cugel the Clever.
Now if you're sick and tired of that sort of mood then how I like to play is not the best fit for you, but it's what goes with the grain of how the basic assumptions of D&D were originally set up. Mike Mornard (the youngest of Gygax's original players) described Gary Gygax's games as Daffy Duck crossed with Conan. And that still works for me 50 years later.
Although with all of this humor it's important to draw a distinction between stuff happening in the game being funny in and off itself vs. things in the game being funny because of our metagame perspective on it. I like the first and don't like the second, I hate things like pop culture references in D&D games and that kind of metagame humor stuff.
The thing is, the Black Company has a consistent tone, even its actually humorous moments, like that time Croaker included One-Eyes horribly written report in the annals. The scene with the ballista is played for drama and it outright increases the dramatic tension, once this fails to kill the bad guy and they have to then jump him, knockin him down (and he doesn't go without a fight), crucify him and feed him something that will burst form his chest like a Xenomorph later.
There is a difference between creativity and players trying to turn the game into a joke by force. There's usually plenty of laughs to go around, but we like to take the adventure somewhat seriously. The "I make villain poop his pants" isn't creative or fun, it's juvenile and effectively laughs at everyone at the table for trying to take the collaborative story we're telling seriously. Not everything needs to have a "Hulk vs Loki" scene and at this point people are fed up seeing it everywhere anyway.,
Haven't really had a problem with a consistent tone in my own games as the games stay pretty much the same vaguely-Jack Vance/Glen Cook tone throughout when I DM. I HAVE seen people use Command: Defecate but only in a game that was already thoroughly lighthearted and jokey due to being DMed by someone else (so Monty Python, not Black Company) so it fit the tone just fine. I would never use Defecate as a Command word in a more serious campaign (use stuff like "Climb" or "Repent" or what have you, while my son likes words like "Spin" to try to make the enemy dizzy or things along those lines).
It's not the same for every game.
Every TTRPG is not trying to be mainstream.
That is the rub. Many of the better games are not willing to make mechanical, narrative, and gaming sacrifices to be mainstream.
For better or worse, WOTC is the only company designing a game that Alice, Bob, Charlie, Diana, and Eddie all are willing to play. And spells like Command are neutered to do this.
In my experience spells like Command that I can explain in simple words "you cast the spell and way one verb and if it works they have to do it" goes over faaaaaaaaaaaaaaaaaaar better with random newbies than a spell whose description is a bunch of numbers. However, knowing how to DM a spell like Command properly as a newbie DM can take a bit of work.
In my experience the kind of game that works best if:
1. You have a DM who's been doing it for literal decades running a game for a bunch of newbies.
2. You have a first time DM running a game for people who have played a campaign or two.
Are VERY VERY different. The games I like are more #1 since, well I'm a DM who's been doing it for literal decades who is often running a game for a bunch of newbies.
However, I'm not sure if you can categorize the main thrust of 5.5e changes as "make things easier for the newbies." The biggest changes to 5.5e seem to be giving more power boosts and abilities to various classes. That doesn't seem like the sort of things newbies would even notice (and some of the new abilities seem to make playing a simple newbie-friendly character more complicated), it seems to be more the kind of thing to make existing players excited and want to shell out the money for a new PHB. 5.5e marketing seems to be very much focused on existing players, rather than existing DMs or people who currently aren't playing D&D.
See, but that's the problem. It's not the spells that are giving them the flexibility. It's playing silly buggers word games with whatever the Dm will let you get away with. Has nothing whatsoever to do with actual tactics which are all about influencing the game world directly.
I talked about this a bit upthread (me trying to reply to older posts in this thread is meaning a pretty big time delay which is screwing up the flow of this conversation but bear with me) but I think there's a division between rules lawyering and in-character cleverness.
I like really specific flavor for spells that nails down specifically what the spell is doing (which can be used by the player in different ways) that gives the DM good guidelines between what a spell can and can't do. I think that Command specifically does this well, which is why I like it so much. Other spells need their flavor spelled out a bit more thoroughly. Then the DM can decide what kind of MacGyvering makes sense and which doesn't. I think there's a distinction between what kind of decisions a character could make about how to use a spell in a clever way (thinking about a clever verb to Command with) and rule lawyering (carefully parsing the exact text of the PHB to do something stupid with a spell) as the first makes sense in character and the second doesn't and it's important to draw a line between them.
For me, if this is all done right it results in MORE immersion as the details of the flavor of the spells MATTER and aren't just there for color (thinks like shoving wax in your ears to avoid Command being a perfect example of this). The metagamey crap should be shut down by the DM. If done right this is EVERYTHING to do with influencing the game world directly.
It's so funny that we have no problems with wizards smashing down the fourth wall in order to be "sneaky", but even the merest whiff of allowing non-casters to do the same is a complete non-starter.
My preferred solution is to keep the ability of wizards to do these kind of shenanigans but nerf them HARD otherwise to bring them into line while giving higher level martials big ways to buff their saving throws and removing/nerfing hard really problematic spells like force cage. I'm no fan of caster supremacy Would like to see martials being clearly superior to casters in things like DPS. I rather like the Mongoose d20 Conan (2e specifically) approach to this in which in raw power the Barbarian class is definitely superior to the magic-user Scholar class but the scholar has some tricks up their sleeve, just ones that are a lot more limited than in normal D&D (with things like lots of casting times measured in minutes rather than rounds).
Using you godly powers, that thing that is most holy to you, to make someone poop their pants? Yeah, not really in character is it?
Depends on the character. Have had some mature and wise characters, have had some immature characters. I wouldn't use Command: defecate in a more serious game. I'm not a dick and don't hide behind "it's what my character would do." I make characters that fit the tone of the campaign. But have played in some lighthearted Monty Python-ish campaigns in which Command: defecate would be perfectly fine.