Marcus

THIS - 100%
 
It is neither easier nor more difficult to calm the same targets down with unlimited Mind Control.  This limitation removes other things that could be done.  The jailer won't unlock the door.  The henchman won't tell you Da Boss's plans.  Mind control can do a lot. This limited version can't do all that much.

I value limitations by looking at the mirror of it. If ‘only to calm people down’ is -1, then ‘for anything other than calming people down’ is also…-1.  If the first is -2, then the inverse is -1/2.  You get what you pay for.

So.. what would you charge this character, in this campaign, for mind control that can do anything *except* calm people down?
 

It could be done with 4e, 5e or 6e, and it was, at least to a large extent, 1e through 3e.
 
Make ACTUAL GAMES that use the Hero System as their engine.  Take that system, with its array of dials and switches and possible ranges of ability, and publish a game that uses the system - that sets the dials and the switches to create the feel desired for the specific game, and presents only those aspects of the rules which are needed to run that game.
 
Perhaps we want a Fantasy game.  It will be Heroic.  So we set our starting characters at 175 points, and 50 points of complications.  Done.  NO OTHER OPTIONS.  You can choose to use different CP, but our game does not.
 
What should their characteristics be?  Perhaps we state outright that no PC can have stats higher than a 20 in any primary characteristic, that few would ever have less than an 8, and that most would have half their characteristics (at most) above 15, and no more than 1 or 2 above 18.   Maybe some races are 3 points higher in one stat and 2 points lower in two others (or what have you).  The point is that we MAKE A DECISION and that is how this game is played.
 
Similarly, we set standards for the secondary stats like defenses and SPD.
 
Maybe we impose greater restrictions - characters cannot have more than 15 in any Primary and similarly set caps for each secondary.  They may then take a single Race template, and up to two Profession templates.  Elves are Agile (+3 DEX), Rogues are Agile (+3 DEX) and Acrobats are Agile (+3 DEX), so an Elf who is both a Rogue and an Acrobat, and buys 15 DEX as a base, can have a 24 DEX.  But none of these templates are especially Hardy, so the best CON he may have is a 15 (maybe some races or professions even have a reduced characteristic).  Maybe you can have as many Professions as you can pay for.
 
We set Skills, and perhaps a starting character may buy only base skills (no extra bonuses), so if you did not invest in DEX, your best agility skill will be 11-.  Some may be in Professions, and maybe we allow for up to X skill levels (or maybe starting characters only get skill levels from Races and Professions).  Perhaps we rename or remove some skills, and set parameters on others.
 
Let's add some Perks and Talents which might be part of those templates, or could be acquired separately.
 
Now, we probably want some Powers, but perhaps we do not call them this.  Maybe we have Extraordinary Abilities, Supernatural Abilities and Spells.  Maybe we have more than one kind of spell.  Perhaps you can only buy pre-fabs (in fixed amounts, or variable amounts - e.g. you decide how many d6 your FlameBolt will do, but a Mystic Shield is always 4 rPD, 6 rED).  Maybe you need specific professions to purchase from certain lists.  We also define our magic system here.
 
Now, if all Wizard Spells require a Wizard Staff, Gestures and Incantations, we don't need to say that in every wizard spell - we just apply those limitations.   Maybe the occasional Wizard Spell can be cast without an Incantation (price it that way, and specify that it is one of those rare exceptions).  Perhaps very skilled casters can overcome these limits (powers built with naked advantages).  No need to spell out the builds.  They could always go in an appendix, or online, but that's not essential.
 
Ditto complications - maybe we remove some we dislike for this game (e.g., no Hunteds; the PCs will make their enemies as they go).
 
We provide the core rules - but maybe there is no Radar in our magical realm (so we leave that sense group out).  Perhaps Blindsense is common, so we write that up using Detect and include it. 
 
We include the combat maneuvers we want, and exclude those we don't.  Perhaps our game will use velocity-based DCV, so we include those rules, and vehicles and mounts, so those rules stay.  No Bases though - PC's don't get to buy a castle.  Maybe we'll include them in a later supplement.  Include those combat rules we wish to use - maybe some maneuvers are not in our game.  Maybe there are no martial arts - simulate them with skill levels, Limited bonuses to CVs and/or DCs, etc.
 
Now, toggle the switches - either we will use wounding or we leave it out.  Same choices for hit locations, Impairing, Disabling, Knockdown/back, Bleeding, Critical Hits - at the extreme, maybe we implement the "ignore STUN" option.  Maybe we include Interposing. 
 
Perhaps we decide characters never recover in combat (reprice Recovery as it is for BOD only, or remove it entirely; a few minutes' rest restores all STUN and END, but running out in combat means you are out).  Maybe we remove END.  Unless we use Long-Term End, we remove those rules as well.  We choose the model of Pushing to be used, and that is the only model in the game.
 
Some environmental effects, like radiation and zero gravity, are not intended for our game, so we leave them out.  Others reflect only those elements relevant - we don't need lasers or electrical outlets, but we have lightning bolts and flaming oil and torches.
 
Maybe we exclude underwater for another supplement, or perhaps we deliberately leave out things like pressure, the bends, etc. - those don't happen in this magical world.
 
Clearly, we will need weapons, armor and maybe rules for magical gear.
 
The point, of course, is that this is not "A system to build any game you want" or even "a system to design your own fantasy game".
 
It is ONE Fantasy game, powered by the Hero System.  You want to do some customizing?  Well, pick up the full system rules and customize to your heart's content.  But our game will stick with the rule book, and any supplements we may decide to publish later.

If you want to impose a penalty, then how about...
 
If my spellcasting does not require a skill roll, then it's at 18- *regardless* of active points...or, if you prefer, my skill rating is such that my net skill roll is 18- even when using my largest active point cost spell.  So if that's, say, 75 points, my skill roll is 25-.
 
That becomes a common basis for a CE imposing skill roll penalties, and lets me cast a 40 point spell despite fairly heavy interference that might shut down a 70 point spell.  The apprentice is gonna be SOL.