Let’s start here: why is he blue?
Giving blue such obscene mana production really isn’t in keeping with the color wheel.
Maybe have a read about Urza’s saga history? It might give you idea why Urza is blue, Karn is colorless and Yawgmoth is Black 
Are we playing the same game? Blue has had the best mana production for a while. I dont think paper magics color wheel influences MTGPQ cards much.
I agree blue’s had the best mana production for a while. Blue does everything better than every color, and it’s rather dull. I’d like to see a balanced color wheel introduced to MTGPQ, instead of blue always just being the best option.
This Urza card is much more in keeping with mono green than mono blue.
Let’s bear in mind that Urza, Lord High Artificer in paper MTGPQ does not suddenly give you extreme amounts of mana production when you play it.
ktagon have taken a card with balanced mana production in paper MTG and turned it into one with unbalanced mana production.
Artificers tend to be blue in paper and will sometimes have artifact-related mana gains (see: Grand Architect, Chief Engineer, Renowned Weaponsmith, and a few others). In paper Urza is blue and lets your artifacts make mana. So that makes him blue and mana-gainey here as well.
I agree that blue has waaaaay too much mana gain in MTGPQ, but that’s more because of cards that have nothing to do with mana having mana gain tacked on (most new draw spells, actually) than because of the few blue cards in paper that have mana abilities being translated as such.
Let’s just nip this in the bud: I’ve been playing paper MTG for 25 years so I’m well aware of what Artificers do, and how much mana blue cards make in paper, and how much mana artifacts make in paper.
What we’re talking about here is the implementation of a card into MTGPQ.
Urza, Lord High Artificer in paper has Create Creature; mana produce and draw card ability.
"When Urza, Lord High Artificer enters the battlefield,
- create a 0/0 colorless Construct artifact creature token with “This creature gets +1/+1 for each artifact you control.”
- Tap an untapped artifact you control: Add U.
- 5: Shuffle your library, then exile the top card. Until end of turn, you may play that card without paying its mana cost"
In MTGPQ , Urza has only mana produce ability. He is already been nerfed a lot compared with paper.
I should actually call Ktagon to buff Urza in MTGPQ
Blue does feel pretty anemic without STV and BSZ. Maybe you’re right and Urza needs. Boost 
My Urza deck is my favorite new standard deck. It’s kind of like STV and gaia’s revenge had a baby
Whether Urza is overpowered or not doesn’t change much to the fact that the balance beetween colors isn’t really coherent in PQ. (Which is what i read beetween the lines in The OP).
It is absurd that blue still give Access to the best ramp cards while green has so few good converters. That’s not coherent with the mtg universe/mehanics at all.
Of course, PQ isnt paper, but magic is magic and it wouldn’t be that bad if colors kept their own personality, strenghts and weaknesses.
The first extensions of pq cared about this much more than they actually do, at least for blue and green colors.