Their are games where using miniatures is a must, Like BATTLETECH... where having miniatures really gets the play going... of course you can use flat maps with the Hexes, Terrain without hexes (using a ruler or pieces of string to determine line of sight and distance) or you can create maps with hexes ( This is my favorite to play on)
Now in most Role Playing games, there are ways to incorporate miniatures if it is desired. There are elaborate setups for dungeon tiles and terrain available for purchase. I prefer the BattleMats as I only want to detail to players what they have to have a spacing for.
Mostly, if there is more than 6 players and 10 monsters I go to the Minis
Back in the day, I used Ral Partha Paints and a Magnifying glass
|Battlemech held in place and ready for detail painting|
Although not as good as the 2 figures I had Professionally done for me, I am pretty proud of them.
|My Professionally done figures|
So, using figures or scribbling on paper is a fun way to add additional dimensions to your game. Like using mood music or lighting...