For basically every multiplayer game, the community will be the strongest in the first few weeks of the game being released. People saying just wait until August seem completely oblivious to how multiplayer works - let alone for an unproven new IP from a game with, at best, a few frustrating omissions. If somebody buys Splatoon, and is angered by the severe lack of multiplayer maps and modes, the fact that in a couple months there will be new maps and modes for free isn't going to make that person less dissatisfied whenever they are wanting to play on different maps or different modes.
Imagine if all you could play in Halo 5 when it launches is Capture the Flag and a ranked Capture the Flag to be unlocked some indeterminate amount of time after launch (but probably not long after), and there were only 5 maps. People would riot! If 343i promise to release new maps and modes over the next 3 months for free, that wouldn't somehow make the lack of content more palateable when the person is most excited to play the game.
I wouldn't exactly call what Nintendo is doing as something that is anti-consumer; but I also feel that Nintendo is releasing a game in an unfinished state in order to hit a release date. That's not something ANYBODY should defend. Either Nintendo is releasing an unfinished game and updating content that was intended to be in the game over the next few months, or they are just releasing a game with a seemingly laughable amount of content (at least multiplayer wise) and giving consumers free DLC over the next few months. Neither of those scenarios change the fact that, again, from what it seems, Nintendo is launching a game for full price that is lacking in content.
Maybe Splatoon launches and has a meaty and very fun campaign. Maybe the multiplayer maps and modes are so good that how little is there isn't a big deal. Maybe Splatoon creates a substantial hardcore following and a consistent userbase over the next few years.
But the idea that a publisher can release a multiplayer centric game with that little content at launch because they will eventually release more for free is not a precedent that I want to be set. Being transparent about a crappy thing doesn't make that crappy thing no longer crappy.