Not to mention that at high-levels, miniatures can become impractical for some battles. When half the party can deliver attacks at a range of 1000+ feet, miniatures become problematic if the combat splits up. Add in teleportation and transit effects, like at will Dim Dooring, magic carpets, mounted characters, flying characters and so on...and minis can be cumbersome or merely a visual aid, as opposed to a solid game component.
Real world example: two games ago, we had a combat with 150 elves against 85 Githyanki raiders, 15 Durka'Gith, 2 Baklash Dreadnaughts, 4 Blackweave Warlocks, 1 undead gith spellcaster and two astral brigs. The PCs consisted of a 21st level cleric, three paladins and mounts (one of whom can fly), a shadowdancer with three shadows who can shadowwalk, shadowjump and use a magic carpet; a shapechange 21st level wizard, a 20th level druid with 7 shamblers, a celestial Roc and his primary animal companion, two arcane archers (one of whom can fly) and 5 swift-runners of Ehlonna.
Minis are only of so much use in such a battle, I can assure you. Especially when the Dreanaughts are breathing fire and using their anti-magic cone eye-rays at a range of 150+ feet, archers are cutting loose at up to 2000 feet and spells are flying every which way at 400+ feet. Minis required? No, sir.