Meh, that doesn't really work. You can't boil an entire colour pairing down to 'insane scientist, always'. Magic already tries to be too simplistic with how it matches colours to personalities (when in reality most normal people have some aspect of all the colours of magic in their personality). Not everyone in the Simic guild was a nutbag strapping lasers to sharks, they guild wouldn't function if they were and it wouldn't manage to support Ravnica like it does.
This is true, but it's also true that experimenting with heredity isn't innately green, either. The reason Simic bio-experimentation is blue/green is that it's built off of using what nature provides as a source and using artificial evolution to reach "natural" ends (see: Simic Vedalken unlocking their dormant second pair of arms with bio-magic.) The Bloodlines project doesn't have that at all; it's explicitly about rejecting the natural altogether and using breeding to produce magical descendants who serve Urza's extremely blue goals.
Again, this gets back to the "what is a four-color character?" thing for me. The reason I think Urza's clearly four colors is that his personality and behavior are pretty much defined by being in opposition to green. This is thematically why the mutual "enemy" of Urza and Mishra in the Brother's War is Argoth (which they destroy without mercy) and why even though he makes it his life's work to destroy Phyrexia he's actually really easily tempted to their side when the chips are down. If you look at everything he's ever done there's surely bits that can touch on green subjects, but the best way to show off his opposition to the philosophy is to make him Breya colors.
You need to consider Urza's goal for the Bloodline Project when labeling it with colours. It was entirely to create what he needed for the specific purposes of combating the Phyrexians and "inheriting" the Legacy. The eugenics side was as anti-natural as you can get and, unlike with the Simic, it wasn't intended to improve or otherwise modify general populations beyond what was needed for his plan.
The Metathran were even more of an ends to a means. They were tools to Urza and nothing more. I mean, they were literally designed to die out after the Phyrexians were dealt with. Just because they were organic doesn't mean there was anything remotely green about them or their development. Think of them more as organic blue "artifact" beings.
Yes, exactly. I think if Invasion was something they did in the modern card-design era (i.e. at a time where they actually vaguely cared about story and mechanics lining up) the Metathran would all be enchantment creatures or colored artifact creatures or have some shared mechanic to establish this.
I take it nothing interesting happened lately or is going to happen until Amonkhet is out
We're in the classic pre-spoiler lull period
and the last significant thing that happened (MM3) was good enough that people don't have lingering complaints to bitch about for the most part.
I still don't entirely understand Atraxa's popularity
You don't understand the appeal of Atraxa, a general designed to play with counters, the single most popular individual design mechanic in commander?
