Agree with OP here, been staying with Marriotts for 15 years now, and I've had to write customer care more times in the past 18 months than in the preceding 13.5 years combined. The whole thing has gone downhill.
When writing in to complain about a property issue, Customer Care seems very quick to reply that "they've forwarded the complaint onto the property and the property will respond to me directly." Or something similar to that. While I'm glad the individual hotel is responding to my issue, many times they are just explaining to me their version of events or re-iterating the terms and conditions. I'm aware of what's written, I want someone to take OWNERSHIP and (if needed) compensate accordingly. Customer Care just seems to be the middle-man these days, shuffling complaints onto the properties while simultaneously not bothering to compensate the account holder.