>implying he wanted to flood only hoenn
It was the entire world dumbasses. And Maxie's objective was to create more land. It's the anthagonism between these two objectives that makes the dinamism of Emerald's enemy teams and ends up with the Rayquaza, Groudon and Kyogre battle.
The concept itself I think it's very cool (pokémon plot standards wise), but the way they explored it on the Hoenn games was pretty bad. They should have way more protagonism, but back then they didn't really have much ideas or will to make the plot a good one. I mean, look at Team Rocket's plot on gens I-II, the Magma-Aqua plot on gen III and compare it to something like team Plasma's plot on BW - it's not even worth comparing.
And even Plasma's plot is dumb as fuck, if it wasn't for N people would complain about Plasma just liek they do for everything else.