This is a huge condemnation of the ride. As Penguin said, the MCU is on the of "indelible pop culture icon" level of Indy or Star Wars. It is the safest of the safe properties on which to base a major ride. Even putting aside its long-term cultural resonance, Guardians is perhaps the least cast-dependent property in the MCU - Rocket and Groot can be recast (as they are in CR) and appear in film after film.
The franchise's longevity and cultural longevity is exactly why Disney parks handling of the MCU has been so shameful, bad enough that it should attract the interest of even notoriously theme-park-averse shareholders. You are correct - CR (and, even more profoundly, Avengers Campus) feel like attractions based on flash-in-the-pan properties, rushed out to capitalize on momentary success but ready for cheap-and-easy retheming when the cultural moment passes. The Guardians do NOT feel fundamental to CR - the ride simply isn't fundamentally ingrained with the IP's aesthetic and sensibilities. And remember how I said Rocket and Groot are the two MCU characters with the longest potential lifespan? That's exactly why not including them as AAs is such an incredibly stupid decision.
Pop culture has NEVER seen a franchise like the MCU - not even Star Wars. The Disney parks need to start acting like it.