There's a vast difference between open ended gameplay and trying to do things with spells like command that are clearly more effective than the example, and what I consider obvious intent, of the spell.
Your example of defenestrate (a word I had to look up and doubt many people would know) is an prime example. For those who can't be bothered to pull up dictionary.com the meaning is "to throw (a person or thing) out of a window". So you mean it to throw themselves out the window. Why? Why not a handy object or other person like the PC that is near them? You're using it as a one turn dominate person where you seem to be defining exactly how the command is carried out.
Part of the fun of the game for me is working within the limitations of the rules of the game to still be effective. I don't try to push the envelope of what a spell or power does because it's just not necessary. Nor for me whether I'm playing the caster, another PC or the DM, is it fun.
Honestly? Well, defenestrate means to throw someone or something out the window... not jump out the window. None of the Defenestrations of Prague (believe it or not it happened 3 times over 2 centuries) involved anyone jumping out a window - they were thrown.
So, word to the wise, don't try to be too clever with your commands.
See, part of the fun of that for me as a player would be
seeing what would happen. That's why I'm casting the spell - I want to do something that's more interesting than just deal damage and cause an effect. I want to play in this space with the DM, where I am using the divine magic of the gods to order a mortal to do something, and the mortal is resisting that command with all their faculties.
I am casting the spell because I'm inviting the DM to riff off of my idea. I don't have a particular end goal I NEED to have happen. The dude throws someone else out a window? Throws themselves out the window? Tosses their weapon out the window? Man, I took that risk when I went off-script, I'm three decisions in (I prepared the spell, I cast the spell, I decided to do something novel with it), I want the DM to take this toy and play with it however they see fit, if I wanted to do damage and have an effect, I had the option, and I didn't want to do that. I wanted to screw around and find out.
If I'm attached to the outcome, I'm not going to choose an off-script
command. If I do, I'm comfortable with an unexpected outcome - hell, it's FUN! It's why I did what I did as a player!
Like, you roll on a table because you want to be surprised by the result. If you don't want to be surprised, you don't roll on the table, you just pick something that works. Similarly, you cast
command using an off-script option because you want to play within that possibility space. If you aren't interested in playing, you have other options for what to do with that spell slot that are more reliable (like a
thunderwave).
And it still isn't clear to me why that is more onerous than, say, someone buying a vial of acid and melting the hinges off of a locked door instead of finding the key the DM hid somewhere in the dungeon. Yeah, maybe it's SUPER effective in solving the adventure! Or maybe not! Not Attached to Outcome! The fun is in lobbing this idea into the shared reality and seeing how it lands.