I have been to WDW four times in the last twelve months and dozens of times this decade, and I do not see a general trend toward less customer service. I have had great experiences with cast members and ok ones. I've never had a bad experience, I guess I've been lucky.
I have had some ridiculously great CM's, like one that made my day special because I'd had an argument with my flight attendant on the way in. That was way above and beyond to me.
I will say that a bad experience early on can color the rest of the trip. I also find that anytime I've had a complaint Disney has been great at responding and that can be a trip reset to get things back on track.
So my advice in the future is politely talk to a supervisor or call your front desk when you get back to the resort. They will get you to the right person to talk to.
In defense of Disney there are two things to consider. January and late summer are when the new CP programs start so the parks are flooded with new employees all trying to learn their jobs at once. Often it is hard to provide the best customer service when you are overwhelmed.
And secondly, T-Rex, like the Rain Forrest and Planet Hollywood, is not owned or run by Disney. So it is hard to expect the Disney service there.