I think Putin was trying to avoid a nasty bloodbath that would create lasting animosity. He was hoping that there would be many Ukrainians who would want to get rid of the Kiev Nazis just as much as him. But alas, as the war progressed, this was a naïve hope.
Putin had seriously underestimated the extent of Russophobia and facism in Ukraine. Years of Western brainwashing, and 8 years of a civil war with ethnic Russians have certainly done its work. Anti-Russian bigotry and facism is very much rampant among the Ukrainian populace, especially in the Western side of the country. Now he has to listen to his generals. At this point, he has to finish this war with victory, no matter the cost. It is sad, but this is war. Putin has to end this 8 year proxy war in Ukraine. War was going to come to Russia anyway if Putin had left the Ukrainian Nazis to fester even further.
The same kinda thing happened to China too during the 2019 Hong Kong riots. China was hoping that saner HKgers would eventually tamper things down. But the Sinophobia in HK was much greater than anticipated. Practically half of HK was anti-China, and this gave massive momentum to riots. People are much easier to brainwash than China had hoped. Only by implementing the harsh National Security Law, China was able to get HK back in control.
The lessons of this Russian war with Ukraine must be heeded by China. A military invasion of Taiwan is gonna be more complicated than anticipated. Winning the hearts and minds of a brainwashed Taiwanese populace is not gonna be easy. They are not gonna greet the PLA as liberators, even when the PLA are actually liberating Taiwan. As this war had shown, war is messy and bloody. China should start considering using its own flavour of Color Revolution or coup d'etat to change the regime in Taiwan. Leave war as the absolute last resort.