While I do agree with the point to some extent, I personally believe that there are several general traits to be judged for a nomination, no matter the type of game. For example, technicality, originality, perhaps mapping, and portrayal of RM well-used overall.
Now looking at the suggestion; even if this was done by voting, the exact same bias would occur due to the fact that, in this case, the community is a RPG maker community. And the majority, would inevitably be, RPGers.
Not to mention that now when there are a lot of random people voting, the actual decision by each individual would become less and less careful as the number of participants increase; resulting in a higher likelihood for people to choose simply what game (type) they like.
Where as when an individual nominee from prior chooses, the pressure of choice is focused on the single individual, which results in a more concentrated and careful choice; because unlike the voting scenerio, the choice of the (only) individual is identifiable directly to the person him/herself (as opposed to anonymous in voting). I believe that this tends to lead to a more considerate decision in terms of overall quality of the choice as a whole.