I couldn't get this question answered by the front desk CMs either, but I have a theory, but it's only that and not substantiated by any facts.
I have never been able to bypass the front desk and just go right to my room. I always do OCI and text notification, even when staying CL. I always get the text telling me to come to the front desk.
I always book using the military RO rate which stipulates that my ID must be shown upon check-in. Though I've never been asked for my ID, I've wondered if the "come to the front desk" text is sent in order for me to show my ID and verify eligibility for the rate. I would assume the same message is sent to someone using a FL Resident or AP rate, but I don't know if that's the case.
When I ask the CM why I had to come to the front desk, they always say they don't know and that it happens "randomly" throughout the day. I feel it has something to do with showing an ID, but the CMs never ask for one so it seems "random" to them.