It's not like those systems need testing Tater. They are ready, past tense. Notice how there are 0 plans for testing or experimenting with Artemis 2 ECLSS, none. Why? Because it is ready, not integrated true, but it is ready. NASA very well could stick LS onboard Orion, it's a choice to save time not to- it's not a matter of "Artemis not ready", it's a matter of what gets Artemis flown sooner. The decision is to skip ECLSS integration, not because it isn't ready but because that moves the launch time sooner.
Saturn V wasn't meant to either by that logic.
Atlas V, Falcon 9, Falcon Heavy- all of these vehicles can't send Orion to the moon. It's nice to ponder on an assemblable Orion but that is not only extremely costly to develop (adding to the costs people already complain about), but also delay the program further. Not to mention that would add additional complexity, failure points (more testing), & also reduce Orion's abilities even further. Why not New Glenn? It's not man rated, has gone through 0 tests to be. We've been through this before, "but why is SLS man rated on the first launch?", for 2 reasons- 1) Most of SLS' major components have already flown 135+ times before thanks to the Shuttle program (RS-25s, Solid Rocket Motors, AJ-10 Engine on Orion Service Module, ICPS (not shuttle but whatever)) - 2) SLS has gone through the maximum amount of testing rigors possible to put an unflown rocket through. Pressure tests? Succeeded. Sound tests? Succeeded. Heating? Succeeded. Safety systems? Succeeded. Despite being unflown- and yes this is wholly an opinion but one I'd put legitimate money on- SLS is one of the safest rockets ever built in history. How can that be? Because again they've tested every facet, of every bolt, of every sheet of metal, of every integration system, with true flight tests to boot thanks to the Shuttle program. As a result, the vehicle will keep crews safe no matter the condition, before the crews ever step inside Orion. New Glenn? It's tests are just to prove it can fly, it has no specification for crew. It's made 0 progress to prove itself.
Arguing cost on the topic of SLS is to argue with a scientist about philosophies- NASA doesn't care about cost. They get their funding from Congress which has a massive sum of money to dispense. When NASA successfully proposes a mission they like (notice, as much as I hear that SLS is just Shelby's initiative, it isn't- since SLS has support from both sides) (also note, NASA makes the missions, not Congress as often as I hear that as well), then Congress provides funding. How much funding is dependent on the scale of the mission they've proposed.
"But Zoo! As a taxpayer I demand better results!" - Not even private citizens remotely have anything comparable to SLS. The only vehicle that remotely can compete is SpaceX's Super Heavy booster (New Glenn's GTO launch mass is 13,000kg vs Orion's full launch mass of 33,500kg). A booster that does not yet exist past an engine, & a render. SLS is frankly, the only vehicle available. "But why launch direct to the moon?!" Because long duration missions lead to greater strains on ECLSS, higher efficiency fuels, like hydrolox or metholox, run the issue of greater & greater boil off issues, which would require a new vehicle to be built that again, does not exist.
But Zoo- I specifically said- what is SLS for?? - It's for launching crews to NHRO to send a crewable vehicle to LOP-G to enable lunar missions. "But Artemis 1 won't send crew to the moon!" - No, since NASA got enough flak for their decision to fly crew on STS-1 in 1981. This mission is to test every component, every part & every module. Past Artemis 1, Artemis 2 will send crew to the moon. Something no other entity, government, private, or otherwise can do within the same timeframe. Starship is said to perform Dear Moon by 2023 though this is extremely unlike as there's 0 work done to make that possible aside from multiple self destructing water towers; Though Artemis 2 will experience some delays as well (I say late 2023/Early 2024- though the next presidency would likely want to secure that chance to send humans back to the moon so an acceleration in pace could be expected), it won't be nearly as severe since most, if not debatably all the testing work has already been completed, meaning only production & assembly must be completed. After that, Artemis 3, will land crew on the moon which is the whole point of Artemis. In 3 missions (2 half missions with pad aborts & 1 of EFT-1, so in total 6 if you want to be pedantic), NASA plans to set boots on the moon. By comparison, the Saturn V flew 2 uncrewed missions, with an additional 4 crewed missions before attempting the landing. Even the Soviet N1 had 4 test flights planned, yes- it failed but there were multiple tests of the vehicle before it did 1 crewed mission. SLS is going to be the fastest vehicle to enable us to not only fly a crewable spacecraft to the moon, but to set boots on the moon.
"But Zoo- why use SLS?! Orion ok, but why SLS?!" To reiterate- it's because SLS is the only launcher that is proven to be safe, passed all tests, & is ready to fly. Orion may not carry crew, but it's not a matter of "it isn't ready" as it is, just not opting to spend time implementing ECLSS.