I should take care to mention that this was in response to the idea of making battles give no reward other than progress. In such a case the random battles might very well become quite an annoying barrier to exploration. But as long as we allow random battles to give some rewards of their own, they become a lot less annoying, even if they are just button-mashers.But random battles aren't necessary for progress unless you make them inescapable, and if you do that you're on the right track to make a very annoying/frustrating game.
The issue is one of balance, as always. In my mind, the correct balance would be something approximating the following (this is going to be the focus of a future article of mine for the Hamsterspeak magazine): random battles give small rewards. They are small enough to make level-grinding and money farming by walking in a circle a very slow, dull task. They are large enough to make exploring vaguely profitable apart from finding anything. To do this we need LARGE areas to explore. Dungeons intensify all of this by adding in the concept of completion. Random battles should be difficult enough that random exploration and wrong turns will lead to the need to retreat due to lack of supplies, but the player does not feel like the trek was wasted because the whole time he was exploring and mapping out the new dungeon, he was gaining small rewards from the random battles. Once the player has the correct path worked out, he or she can complete the dungeon.
As for the possibility of players mindlessly grinding to reach astronomical levels, ask yourself this question: Given the option to level-grind, would you? I said "option", not "requirement". As long as level-grinding is not required, why worry about taking away the option? Its harder to do, but we can try to balance stat gains so that short bursts of level-grinding are not very profitable to the player.
Yes, I enjoy the Dragon Quest series more than the Final Fantasy series.