Partly, that is what I'm saying. The technology of the suits is internalized -as you mentioned- and is suggested in the negative space of the aesthetic of gameplay and narrative. For example, the player can see that Shepard uses a type of counter pressure suit instead of pressure suit for vacuum which is made from exotic materials that appears to self-seal among having other qualities. There is no need to clutter the visible aesthetic with layer upon layer of external glamorizing or have idiot ball conversation with NPCs to validate by explaining in game such aesthetic choices. Such things create branches of thought that distract from the story and setting as well as take up resources better spent elsewhere.
There may be no need to add more visual detail, but that doesn't mean that more detail is necessarily a bad thing. The concept of layering various materials over each other inherent to ME2's designs evokes a more realistic construction and implies that a greater amount of thought was put into making this piece of technology. It seems more relatable, which for amor–a thing you're supposed to slip into–is a good thing.
The same can be said about expositional content. If this were a movie with a limited run time, sure, having exposition about armor design is useless, but this being a game, time is not nearly as big a factor. The writers could whip up a few paragraphs in their spare time explaining the armor construction process, and as long as the player gets to choose whether or not they want to hear about this stuff, it's not detrimental to the pacing. The sheer quantity of codex entries in the Dragon Age games makes the lore and by extension the immediate world appear more real.
I also seriously disagree with the notion that ME2-3's armor is cluttered; their designs have more visual elements, but they follow a nice flow. Other than a few LEDs, there are very few frills.
There is no mention that I'm aware of that says armor technology is nanotech, that was something that seemed implied by the aesthetic and functions of the suit in ME1. There could be other fictional explanations or it may have been a limitation of design.
I think you're conflating intentionally sparse design with lazy design and technical restrictions.
This isn't The Hills Like White Elephants, I don't see any great thematic or stylistic benefit to leave armor design in such an ill-defined state. At most, the alleged negative space implies that it's the future and people have access to materials which seem effectively like magic to us. Sure, the futury connotations are nice, but it comes at the cost of lore. The Mass Effect games do a fairly decent job keeping most technology within reasonable technological evolutionary standards. Eezo and some of its derived technologies stand out as the only advancements that are effectively magic.