In the basic rules, what allows you to make a melee attack is taking the Attack Action (or other bonus actions/reactions that allow such). Anyone can make a melee attack, but not if they choose to take the Dodge Action, for instance. But the person who used Booming Blade did not take the Attack Action, but the Cast a Spell Action. Ordinarily, you can't take the Cast a Spell Action and also make a melee weapon attack on the same Action, unless the spell says so. But if you take the Cast a Spell Action and the spell gets cancelled...
Sure, and nothing stops you from running it like this at your table. But there is nothing in RAW that determines it to be like this. And the fact that there are rules that say they work differently in a specific environment (the vacuum of Spelljammer Wildspace) does not allow you to conclude that they also work differently in an entirely different environment, specially when there are rules about those other environments, in the core book none the less, that don't mention such differences.
And I'd really like someone to address my argument about Lesser Restoration and Blinding Smite, and if you agree that Lesser Restoration indeed cures the Blindness of the Blinding Smite even without addressing the spell specifically why does the Tidal Wave extinguishing unprotected flames does not extinguish the unprotected flames of Wall of Fire, just because it does not address the spell specifically.
Perhaps relevant to this discussion: Jeremy Crawford has actually stated that Disintegrate works on Forcecage, even if neither Forcecage or Disintegrate mention each other directly.
This thread has been very informative for me, and has led me to realize that a lot of assumptions I had about the game have no basis in the RAW. Disintegrate not working on a Force Cage was one of them, for instance.