So far this year Nintendo has had Mario vs Donkey Kong Tipping Stars, Kirby & The Rainbow Curse and Mario Party 10, so it's not like they've had no retail exclusives this year. Those titles may not be huge exclusives, but they are something, Kirby reviewed reasonably well (75/100), the others not so much, but it's better than nothing.
Nintendo could do with a Direct for Devil's Third, Splatoon, Mario Maker, Kirby, Xenoblade Chronicles X and Starfox (that one could just be a small teaser like the Zelda stuff).
I don't think they should wait until E3 to announce release dates for those games, they need to show they are focused on Wii U right now.
E3 should be for new games to be revealed, but a Direct to set up the system for the rest of the year definitely wouldn't go amiss!
