Those two rural/small town walks you mentioned: can they be accessed without driving?
The henro-michi is harder to get to, because Shikoku in general is harder to get to. If coming from Kobe or Osaka, you'll probably want to take a bus to Naruto, Tokushima, or Takamatsu. (Naruto if you're starting from the beginning.) A bit more of a schlep, but still not bad.
If doing these walks, then not driving is a big advantage -- because you don't have to worry about where you parked your car! In particular, you don't need to end at the same place you began.