Pretending that integrating anything into the system is "free" or even nearly so, is plain naive. Adding even something as seemingly innocuous as a new emoji entails updates to repositories, test plans, test procedures, and the execution of those tests to validate the procedures themselves. Then you incur some portion of the regression testing/documentation costs in perpetuity for as long as that "thing" is part of the system. That's not even including the up front work that resulted in the ultimate decision to include the "feature" in the system. Resources are expended even if there is little to no "coding" involved.
With that in mind, it is entirely fair to criticize Apple for spending what we all assume are limited (albeit, possibly quite large in Apple's case) resources on a feature that, as implied by the tone of your post, appeals primarily to younger users when features with potential for a lot more universal appeal continue to lag. For example, as a "geezer", I would find Siri infinitely more useful than emojis, if it didn't fail miserably at providing me with a useful response 40% of the time I try to use it. So if Apple wants to provide emojis, fine. Complaining that they appear to be doing so at the expense of functionality, stability, or convenience in other areas is equally fine.