Mebius doesn't have that holding it down. The closest it has is a reuse of Windam and Miklas, who are redefined here and are pretty much characters in and of themselves.
Whenever an old hero shows up in Mebius, it's few and far between but it matters a hell of a whole lot and really adds to the message of the episode.
Because the series is about more than the fanservice. It takes the fanservice and blends it into the story, so it gives us neat moments like Twintails and Gudon fighting again, a classic moment of the franchise, while giving us a good story and great character development spaced across the series.
Gokaiger's fanservice just feels fluffy in comparison, more flat and meaningless, by and large. The best bit was the Jetman episode, as I've said before. If all of Gokaiger used that as the baseline, the series would have been a lot better in my opinion.
It didn't. Instead, Gokaiger is just really a lot of flash without any real substance, junk food for the eyes and a quick shot of nostalgia.
Remove the fanservice and the anniversery aspects of Gokaiger and you'd get a series not a lot of people would like, I'd argue.
Remove that from Mebius and you still have a damn solid show.
Carrying on from above, simply that the show itself is solid before the fanservice. If you took away all of the returning characters and Gokai Changes from Gokaiger, you're simply left with static pirate characters fighting bland, misused and underdeveloped villains until all the bad guys blow up. Though Gai would be a fair bit more interesting, I think.
Do the same with Mebius, and you still have that great character development, those great villains, and the unholy master of disaster Enpera himself showing up.