Not to mention that the N7 armor looks a lot more advanced than it did in the trilogy, especially the first two Mass Effects.
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In other words, we're looking at post ME3 timeline.
My theory is that the Reapers destroyed so much, no matter what ending you picked, that the galaxy largely has to start over and explore again. You'll probably come across a lot of worlds devastated by Reapers, and you'll explore them in addition to new works untouched by the known galaxy.