
'There is nothing to do,' said Bingo, 'except to go home. Which is difficult for me, as I haven't got one now. i shall just have to go on, as the Elves advised. But you need not come, of course.'
'Of course not,' said Marmaduke. 'I joined the party just for jun, and I am certainly not going to leave it now.'
Then, after Marmaduke suggests that they avoid the Black Riders by entering the Old Forest, eliciting a protest from Odo (sort of Pippin's predecessor, but not really), he states:
'It seems to be silly, anyway, when you are beginning an adventurous journey to start by going back and jogging along a dull river-side road.'
I think this shows the real reason why Tolkien had the Hobbits enter the Old Forest rather than stay on the road: to provide them with an opportunity for adventures.
Even in the following intermediate version of this chapter, which moves much closer to the final version, the objection to going into the Old Forest (still given to Odo), centers on the fact that the Riders themselves would likely be more dangerous met in the Forest than they would on the Road. This is an argument that makes a fair degree of sense to me.
Turning back to the dream at the end of the chapter, Scull and Hammond are correct of course that it goes back to the original version of the chapter. But there is a small but significant difference between both the original and intermediate versions, and the version in the final text. In original version, Bingo seems "to be lying under a window that looked out into a sea of tangled trees." In the intermediate version, he seemed "to be looking out of a window over the dark sea of tangled trees," almost the final language, but missing one important word. In the final version, he "he seemed to be looking out of a high window over a dark sea of tangled trees." The fact that Tolkien went back and added the word "high" into this sentence suggests to me that while the snuffling originally was meant to refer to the Riders, after he wrote the scene in Lothlórien in which Frodo was high up in a tree tower looking over the tangled forest of Lothlórien, with Gollum crawling and snuffling at the base of the true, he added this additional word to make this dream better anticipate this later scene.