Earlier quoted context omitted.
Job done well enough that internal emails at Apple said, "the #1 most difficult [reason] to leave the Apple universe app is iMessage"? Come on. Apple's VP of software engineering would not be debating Android support in internal emails if SMS worked "perfectly well".
I agree that Apple not bringing iMessage to Android is lock in and very purposeful. But I don't think (at least not initially) it's because it works better than plain old SMS. I think there is quite a bit of social pressure to have "the blue bubble" especially in middle/high school. Most of the iMessage features, text, video, pictures and "reactions/tap backs" work over SMS. The only real feature missing is delivery…
Other than 'text', none of those things use SMS:
Sending pictures and videos uses MMS, which is one of the most flakiest parts of the old feature-phone ecosystem because it's inextricably tied to the level of support from both the sender's carrier and the receiver's carrier for particular MMS message content - and how carriers love to charge insane $-per-byte for SMS/MMS content. While in the US exchanging video MMS between the 4 (or 3...) major carriers you likely won't experience any problems provided the video is under a few megabytes and using a well-supported codec like H.263/H.264, if you see what it's like for the rest of the world (Europe, India, etc) you'll understand why services like WhatsApp are so popular: because carrier SMS/MMS service is awful... if not obscenely expensive.
The "reactions" thing you mention, to my knowledge, is not supported by SMS either - it's either an Android-specific MMS extension or you're using RCS - and Apple has no incentive to support RCS, excepting any kind of laws requiring phone carriers and handsets to fully support RCS (I wish...) in order to be sold in a giving region.