It is more than 200 miles for infantry to move through enemy territory. No base of supply and unknown intelligence about Confederate units may have been a major factor. That means 400 plus miles out and back from your assigned area. This was the type of operation that Cavalry under Stoneham could do with less problems the next spring.
Because his mission as directed by Grant, was to make the Valley unusable for the Confederacy in all aspects, and that is what he was doing. Cutting a railroad is temporary and will be repaired. The Burning was much more impactful long term
It's almost 200 miles away. That's really tough on horses.