Hey Mark, as a limited main I wanted to say that I'm a huge fan of the kinds of cards that we've been getting lately that let us play with all time high power-level effects brought down to a fair level for limited. MKM had a fair Control Magic. OTJ has several, including references to Demonic Tutor, Ray of Command, and Snapcaster, all at uncommon. It's exciting to get to play with classic effects in a way that doesn't disrupt the balance. I'm the most eager to draft I've been since MOM!

It’s an area we’ve been enjoying exploring recently.

Why are some effects (discard, counterspells) restricted to one color, but others aren't, even in cases where you don't want too many of them (control magic being secondary in black, spell redirection being in blue/red, stealing opponent's cards in blue/black/red)? Shouldn't all infrequent effects be restricted to one color?

No, it varies based on the effect.

I earlier asked "With the benefit of hindsight, do you wish that Planar Chaos had adopted a sixth color as its main "alternate reality" identity, rather than the color-shifting that actually happened?" and you answered "The sixth color only worked if we redistributed the color pie which is the problem in the first place."
Would you be willing to elaborate further? My understanding was that planar chaos was a problem because it gave colors access to effects that they should not have had. But if you redistributed pieces of various colors to purple, then each (non-purple) color would only have access to effects they had before--they'd just have somewhat fewer of them, and perhaps a different emphasis (i.e. if purple took hard countermagic, then maybe blue would lean harder into control magic for the block). That wouldn't introduce any color breaks, so from a color pie perspective, why is it a problem?

The inability to redistribute would make adding purple harder, but you’re correct that what you’re suggesting is theoretically possible.

Hi MaRo, thanks for all your hard work making Magic. Both Control Magic and Time Walk effects are massively powerful, with Time Walks getting banned even at 7 mana. Is it possible that these effects should get the "Vindicate treatment" of being only doable with two colours?

A second color isn’t the safety valve you think it is. : )

"Theft is still in blue. (Well, permanent theft" Is it secondary in Black? I know there's been some in Black before. Captivating Vampire and Enslave come to mind. Taking someone else's stuff for yourself seems like a very black thing to me. I know this is a case of tradition, with Control Magic going all the way back to Alpha, but I'd be a big fan of seeing it less in blue and more in Black.

Stealing is tertiary in black. We do it on rare occasion.

Hey Mark! My friends and I were having a discussion regarding the interaction of animate library and control magic. How does card draw work? If my opponent controls my library, can I just not draw? Do I die from not having cards in my library? Can my opponent choose to draw from my library?

Animate Library falls off if you ever lose control as it can only animate a library you control.

if ive animated my library and an opponent takes control of it (e.g. control magic) can they draw from it?

The enchantment drops off if it gets stolen as it becomes an illegal target. Your library then reverts to being your normal library.

If Control Magic were reprinted today, would it be mythic just for how backbreaking it is in limited?

It would probably be rare.

Would having more Mind Control and Control Magic effects at common and uncommon solve blue's need for a "creature" mechanic?

No. Development has actually chosen over time to move the mechanic out of lower rarities as they are very brutal in limited.

Could red possibly get a control enchantment similar to control magic but give enchanted creature an effect that is very red-ish like "This creature must attack each turn if able"?

Red can steal for a turn but not permanently so adding a red rider is not enough to justify it.