I think it would have made sense to get out a lot of early demos for game feedback to at least make sure it was an excellent product for what it was, and maybe try and make the Metroid theming stronger by having you play more prominent characters in the universe and any other adjustments that made sense as feedback came in.
I'm skewed more toward multiplayer gaming personally, but given the series is historically singleplayer, it would have also made sense to offer a much more accessible singleplayer balancing as well.
Beyond that, I would have been very upfront about the future plans for the series. It's fine if this was the only planned product in the universe, but they should basically lay out "This series doesn't do especially well so we're trying a new approach so that we can continue it in at least some form and would like to work with people to make this more appealing." If there is a new game coming, they could have also asserted that was definitely in development the same way that XCOM the FPS would have benefitted tremendously from Take-Two just explicitly saying that Firaxis was working on a more traditional game that would come at some point in the future.
Or, put more simply, they should have asked themselves "Why is this game a Metroid title and why would people who like Metroid actually want to play this?" and started trying to answer that with the product. Otherwise, maybe they would have even just been better off rebranding the thing and then messaging on it entirely on its own merits. Nintendo got a Zelda Musou game to work for their audience and appropriately encompass aspects people liked about the series however, so I don't think this was an impossible task even with the IP attached.