Concern Over Lack of Promotion: Is this Unfounded?

This. There's been a pretty big trend in the past few years for games to be advertised in shorter, more intense marketing cycles than the long ones we've seen in the past. Bioware seems to be taking a page from games like DOOM, Fallout 4, Civilization VI, and XCOM2 (just off the top of my head) as far as marketing goes. Whether that's a good thing or a bad thing is open to interpretation, but if I had to guess, they're reasoning that they have enough ME fans who will buy Andromeda at or shortly after launch regardless of how it's marketed, and there's no point in marketing to people who refuse to pre-order at all.

Also, Andromeda is the first time since DA:O that we've seen anything like new IP from Bioware. We're getting at least two entirely new major species, plus a new precursor-ish species, a completely new cast, and a whole new galaxy of lore. That's all the sort of stuff that's best experienced in the context of the game itself. I would be interested if they put out an article talking about, for example, how the kett government works. But the entire point of the game is exploring a completely unknown galaxy. Ryder will, presumably, interact with the kett government not knowing how it works, and find out through that, at the same time as the player. If they tell you, it would ruin that.