Earlier quoted context omitted.
Not just that, it's removing barriers for competition. Which is what good regulations is all about. (and, technically it more than just bubble color, it's also including everyone in group chats)
I think what the (grand)parent would argue is that this isn't removing barriers to competition, it's removing competition itself . That is, iMessage is a feature provided by Apple that makes their products more compelling as compared to their competitors. By requiring Apple to provide this feature to their competitors, they lose one of the key differentiators that make their products "better" than their competitors.…
That's pretty funny considering the European Commission's original complaint against Apple was for anti-competitive behavior.
Maybe things would have turned out differently if Apple hadn't embraced, extended and extinguished SMS. Maybe regulators would be a little more lenient if the App Store was ruled with anything other than an iron fist. But now they have to take action, not because Apple is unique, but because their business practices are interfering with the progress of the rest of the industry. Competitive agency is a weak excuse when they're a noted tyrant on their own platform.