Depends if the character fantasy you're trying to realize is "Dedicated Pokemon game completionist" or "Ash and Pikachu". The latter is the image that has more demand, and the one that Chain Warlock comes closest to satisfying. It still comes up short, but then that's what people are asking for changes over.
Really, I don't see why you're so opposed to the idea. It's not like Chain Warlocks are particularly popular as they are right now. Why not make this an option, especially if it's genuinely optional in the form of Invocations you can take or pass up as you please?
Because the image conjured up by "Ash and Pikachu" is one in which your companion does most of the fighting rather than you.
As such, it would have to have combat stats close to a martial player character, since the Beastmaster and Battle Smith's (both only
half casters) companion seem to be regarded as too weak for that archetype.
Thus attaching a more powerful companion to a more powerful full caster chassis doesn't seem like a good idea, unless the character is actually having to use those spell slots - for example as a Shepard
Druid or Conjuration wizard would.
I think that Salthorae's suggestion is probably the best bet, using the conjure spells but ask the DM to generate higher-CR versions of your creature as you access the higher-level spells, rather than summoning random varied creatures.
An alternative would be to generate a Fighter or maybe Monk, ask the DM to refluff it as your monster of choice, and use the Retainers background option to represent your noncombatant trainer perhaps?
Or perhaps a Beastmaster or Battle Smith but use your spells, infusions etc to buff your companion?
So you now want to nerf 8/12 classes because they are too strong. Imbalanced. Relative to what?!
Relative to the other classes and the amount that, other factors being equal, a player of those classes can contribute to the story in all of the pillars.
Balance requires something on the other side of the scale.
Or the line. If it help to understand the point that he is making, think of it this way: There are classes that are much "heavier" in power to achieve things for the party, and there are classes that have less power, or are "lighter".
What problem, exactly, wouldn't be fixed by patching 2/12 classes or even 4/12 classes simpler than nerfing 8/12?
And game mechanics wise, it is ridiculously easier path to patch up 2-4 classes with their issues than tear 8/12 down.
I'm guessing that Tony would be fine with buffing up the other classes to match the top tier.
But until that happens, I think it likely that he will oppose most buffs to the classes above the line that would make them even more powerful than the ones below it.
So you are saying that roughly half the classes in the game are drastically underpowered and so devoid of anything that makes them unique or interesting which could be improved upon that the only solution is to nerf the other remaining half? That about right?
I'm pretty sure that the "devoid of anything that makes them unique or interesting" hyperbole is just something you made up.
Personally as long as the rest of the game keeps up, I'd be fine with buffing the other classes rather than nerfing the overly capable ones.