Do you use Miniatures with your Games, being "Old Skool" I do - even though WotC have pretty much made it mandatory to run games effectively now that you HAVE to use a battle grid and miniatures making combat more like a tactical wargame - I don't really use them in that way.
They are there (at least from my own perspective) to -
Its a far more evocative scene in a Tavern (for example) if the Players know where their characters are standing in the room, where all the exits are, and exactly where the "Mysterious Stranger" is standing - and (hopefully) exactly what he looks like.
How many times has a player argued his character wasn't standing there when a trap went off, or he wasn't "at the back" when those Orcs attacked. If the PC's miniatures are lined up in "marching order" there can be no arguments of that sort.
Scare the CRAP out of your Players.
You are attacked by 10 rampaging Ogres" is no where NEAR as scary as actually putting out 10 Ogre Miniatures, then telling them to roll for initiative. Likewise a Beholder looks scarier "in the flesh" on the table, indimidating the party!
But not in a move your miniature and roll your attack sort of a way, in a broader more role-playing friendly manner. Who has line of sight to what, can the Thief get near enough to attempt that Back_Stab, or is everyone too close together for the Wizard to attempt that Fireball.
There are most likely to be many MANY more reasons than the four I have listed above, Miniatures should be treated as a tool to enable your Role Playing - they should't be allowed to take away from it (I'm pointing at you Wizards).