Well, Yawgmoth actually gave phyrexians their expansive ideology, right?
He probably wouldn't lead an entire civilization to global conquest if he wouldn't think there is something in it. According to MTGsalvationwiki
he viewed Phyrexia as perfection before it was so brainwashing. Maybe juuust because
"being a phyrexian means being immortal, ethernally happy, and in an absolute harmony with your kind" ?
That's for all intents and purposes
Propaganda. Sure, Yawgmoth might have believed this stuff himself when he discovered Phyrexia and the oil, but in the end it was just about seizing more power and taking revenge on the Thran. He had seized power over a good portion of the Thran empire before he even started turning people into Phyrexians, and it was basically a fascist military dictatorship. Becoming the Father of Machines was just the next logical step. So I would argue that Yawgmoth's goals were messed up and selfish to begin with. Besides, if it had been about happiness and immortality and all that, he could have stopped much earlier.
"Planeswalker says Phyrexians have neither a concept of nor a word for 'happiness'. Being happy is not in their nature and irrelevant to their purpose. In a way, that's all they have: purpose. "
Precisely !
If you have a concept of happineess and unhappiness, if you are constantly pursuit first and run away from the second, you are not ethernally happy.
If you don't have a concept of happineess and unhappiness, if you only have your "purpose" as an only motivation, you are really, absolutely happy.
Not knowing happiness isn't the same as being happy. Even if it was, no-one could bear constant happiness.
But there is a quote where new phyrexians desribe their work as "Joyious". I don't think new phyrexians are that unemotional.
The red faction seems to have some sort of compassion with the Mirrans while the white faction follows a quasi-religious doctrine (but in a way, so did Old Phyrexia). I'm deeply suspicious about their use of the word "joyous", though. I find it much more likely that they use that to mean their work is in line with their goal and their purpose, and maybe some of the factions use it to differentiate themselves from the others, because their takes on what Phyrexia should be are all pretty different.
"Whether you call them 'evil' or not is semantics, they're bad and need to be opposed either way."
True about Eldrazi, because they want only obliteration. Not true about antagonists that want power - like Bolas or New Phyrexia.
Thing that really matters is how they want to use their power. Bolas just wants to tyrnanize everyone, New Phyrexia wants everyone to
be united
be immortal
be ethernally joyious
be more logical (You would sacrifice yourself fo a greater good ? Now you will do in in a most effective way possible, and without any regret. You pursuit knowledge ? Becoming a part of a supercomputer is the most effective way to do it, and you would do so happyly. Etc etc etc...)
have a wierd aestetics
spread things listed above.
The Eldrazi are like a forest fire, but Phyrexia is like a virus. Both will be opposed by the people threatened by them if they have the means, even though the forest fire and the virus just do 'their thing'. And from the perspectives of the people on Dominaria, Mirrodin, Elspeth's homeplane and all the other worlds that have confronted Phyrexia, it must have felt A LOT like obliteration at best and as something even worse at worst. Sure, technically they are united and immortal (but not joyous), but what use is unity if it kills individuality? What use is immortality if your life isn't your own? Or your mind and body? Also, the notion that tyrannical people who want power don't need to be opposed is profoundly messed up.
Not THAT horrifying, right ?
VERY horrifying indeed.