You can say that about a lot of writers, though. Byrne was accused of focusing too much on Lee And Kirby on FF.
Levitz keeps me interested, but that's about it. It seems that this Legion is as much of a shadow as the groups of the past 20+ years have been.
That's been one of the longest problems in the LoSH with creators, they only use what they like and toss the rest. That to me is not the least bit professional. It's also the problem with fans turned pro too. They may bring some great stuff in as fans, but they also bring in the crap that should be left at the office door or better yet, at home.
Johns tries to make it work, but sadly failed. It may be a case of this is one set of characters he just cannot work with or he was burnt out. Sometimes a plate can be too full.
Don't get me started on Johns. He tried too much to try to go the X-Men route with the humans vs. alien stuff. And he seemed more interested in bringing back Superboy and Bart Allen in Lo3W than he was using it as a Legion: Rebirth.
Johns only seemed to be interested in the Legion as a part of his stuff on Superman. As soon as he dropped that, he dumped the Legion as well.
Levitz lost it. His work is like all the rest. Dumps characters for new ones, treats others like crap for the sake of bad melodrama and these days goes PC and makes it hard to like at all because of it.
Bringing Levitz back was either a bad move due either to a) nostalgia, b) part of the deal with getting him out of his job as publisher (president, whatever) of DC. Or both.