I think these movies should lose the "All" part and just stick with the traditional small "dream team" aspect so it doesn't seem like a giant mess.
But they're only starting to actually be "All" movies with this one. All Riders vs Dai-Shocker had guests in the beginning and ending, but Let's Go took a big step back and only had guest Riders near the ending.
This movie is juggling two different franchises, and focuses on Decade and Gokaiger, but at least it's attempting to use various series throughout the movie. Besides, a "dream team" might be kind of traditional for Sentai, but Rider has always just brought back everyone.
And, really, Yonemura's work under Shirakura always seems to be considered a "mess" by many people here, even if it isn't a big All Riders crossover (See Kabuto and its movie, or even Decade's conclusion itself which didn't involve "All Riders"). So, whatever. Cutting the number of heroes won't change the writing style.