Yep. Activision and EA won't be attending E3 at all, which speaks volumes about how the event is losing relevancy.
Hardware versus software.
E3 is losing software relevance because of the rise of digital direct and mail-order (Amazon) sales. Particularly, EA has their own digital release platform they would prefer to push over traditional retail, and Activision's most successful outlet (Blizzard) has their own dedicated digital storefront and basically releases online-only games (which have the least need or want for retail space, often not having retail releases
at all of all non-mobile games).
Hardware is not software. Hardware still relies on brick and mortar retail outlets primarily for sales. Nintendo, in particular, seems to have smaller shares of mail-order hardware sales, fewer dedicated outlets (ie, Microsoft Stores), and are by the far the most reliant on impulse buys, as evidenced by how much of their sales are made during the holiday season.
E3 is important to retail partners. That's why consoles traditionally debut there: it gives retailers enough forewarning for shelf and warehousing space to be allocated and supply chains to otherwise be prepared, as these things need to be ordered by retailers well in advance of their actual sale on shelves.
Nintendo is already in a shitty position with retailers because the Wii-U ended up overstocked basically everywhere and didn't provide nearly as much software to push as promised (retailers prefer software, since it feeds into their resale systems and the margin is generally much better than hardware with respect to shelf space). They're in an even crummier position with a March release, given that retailers know they historically don't sell hardware units well outside of the holiday season.
They really aren't in a position to be losing
more retailer confidence by just not showing merchandise at trade shows. This is entirely a case of a god-awful bad scenario they didn't want to be in, but probably deemed the less-bad choice for other reasons (supply line problems with the hardware, development shortfalls for software, etc.). This isn't a preferred strategy of any kind.