And yet, with all of that intel, they're still bleeding troops at a 7:1 ratio with Ukraine.
As for destroying cities...
The key to this strategy is to eliminate defensive positions and potential defensive positions of the enemy. Aside from the humanitarian issues, the strategy works if, and only if, the attacking side has the plan and logistics to capture and hold beyond that point.
The Russians have shown their lines are heavily susceptible to counter offensives. By leveling cities, the Russians ensure they don't have a fall back point, causing them to give up more territory in the event of a retreat. During the Kherson offensive last fall, the Russians couldn't run away fast enough. Many were killed while retreating. Without the ability to set up defensive positions within the cities they capture, they will have to rely on trenches and dirt mounds, which fall quickly under Ukrainian attack.
TL;DR - By leveling cities, the Russians stretch the no-mans land which put them at a disadvantage in the event of retreat.