When you use minis, you're tacitly agreeing to certain prominent aspects of your game.
- Visualization is important. You're going to want to know where you are in relation to other creatures. This makes "realism" trump "cinematics": it's important to be accurate about what is simulated, and small differences in interpretation matter, and need to be clarified. This makes combat important, because combat is mostly when you need to know this. Combat is "strategic," that is, simulationist, rather than "cinematic" for this reason.
- Your combat, in using minis, is limited to things you can represent in gridspace. You have required accessories (battlemats, minis, grid templates), mostly for combat. This increases the investment and importance of combat in your games, too.
- Your combat, due to having rather extensive set-up, should be very important to your games. In fact, it should probably be the defining characteristic of your games. Otherwise, it's not worth the investment and set-up for each player.
- Because it's such a defining characteristic, other things naturally diminish in importance. Interaction can't be important, it doesn't let us break out the minis! Exploration can be fun, but it needs to lead to big combats, since otherwise it doesn't matter where on the grid we are!
- You are committing to producing a line of minis, so character customization diminishes. It's great if you can use the fighter mini also as the priest mini and also as the thief mini, so pallette swaps become key. The more customization your characters have, and the more unique kinds of races, classes, etc., that you have, the more difficult it is for you to keep them supplied with accurate minis. Related, monster customization should be light, for the same reasons. You can easily reduce this with tokens or chits, though.
These things can be more or less true for different games -- certainly people used minis for combat even when they weren't necessary or well-utilized, and a lover of minis is going to probably get and paint a mini to represent their character even if its superfluous. I'm sure plenty of people have played intrigue-heavy games with their minis sitting around miniature tables just because it's fun for them. That's great, though I'm not sure it uses minis to the full extent that they could be used.
My personal opinion is that minis are quite a bit more hassle than they are worth for my own games. I would much prefer a cinematic battle system that doesn't require me to know the exact distances between things or accurate battlefield and character representation. I want to fight airship pirates on the falling body of a dying dragon, spiraling out of control, through wind and hail and lightning. I want the party to consist of an elf, a dwarf, a sentient mop riddled with termites, and a magical sword who is currently possessing a giant spider. I want the monsters to be unique chimeras of lungfish and billy goat. There's no way I'm going to try to accurately represent that combat on a grid with figures. It's too much for minis to handle. It's too dynamic, fluid, unusual, and changing.
I grok that not everyone has quite the...cinematic flair...that I tend to have, vastly preferring the strategy of grids and ranges, which is cool. But after trying to fit my complicated peg into 4e's square hole, I gotta say, I want something else.
I've gotten close in 4e. Fortunately, my players do enjoy the cinematic style. But it's pretty in adequate, and can only be used once in a while.