There is no card you ''need.'' It all depends on the strategy and the opponent. It is a very strong anti swarm card. It can finish a ROL deck too. (Neptune sure gave me a hard time.) It is not that expensive either. Just let the opponent fill the screen, stall a bit. Halfway you flood the screen and confine the opponent to the centre for the rest of the match. Even if it's just for 5 or 10 turns, it does what it has to do. If it drains you too much, smash it to bits with the pulverizer. You don't always need it, after it has killed a few dozens.
If people don't like the card, they're not going to play it. I think that it is very good, especially when used on the right opponent. It can give you 100 bone wall charges, especially if you drown your own skeletons. I can understand that may not be for everybody, but I happen to think it is a very funny card.
The weakness is it doesn't work on the first 7 opponents, yes. To beat ''quality'' opponents you are better off with antimatter/aflatoxin or something. They're each others opposites. I play both strategies, and an inundation gives a much better lock on a swarmer. Is just mass CC versus isolated CC. If people always play a handful of quinted units, it will not help. But then neither will most CC cards.
I am not sure this is always the case though. I see plenty of fractaled little critters. (Pest/ROL)