Also, you need to always be aware about walls nearby and chars surrounding you. Each tile around you where you cannot step reduces dodge rating.
Exactly. The only times when you won't be surrounded by enemies, allies or scenery is in the arena. The majority of fights would have you surrounded by something, and every time you move you open yourself for opportunity attacks. Nothing better than being hit for 15HP for free, isn't it?
Blocking gives you three levels of defense. First is to completely neglect the damage, and as we know, it procs better because it is not affected by your surroundings. Flanking and rearing will be introduced only in Dungeon Rats. Then, if it fails, your shield absorbs some of the damage. And only then the damage comes to your armor, and as a blocker, you don't really care about armor penalty, so you can wear actually good armor.
With dodge, you have only two levels. First is dodging itself, which procs worse than blocking. And then it comes immediately to the armor, and as a dodger, you won't be usually having the toughest armor.
The only advantages dodging gives is by allowing you to use two handed weapons and don't suffer from shield THC penalty