The Light/Dark only for Cleric/Sorcerer etc had to be implemented due to the story I guess.
I also find it very restrictive.
When playing Light I don't have much choice but to build my characters for melee, Paralyze the deadly enemies and whack away.
Fire Blast from MM6 was replaced with crummy Fire Spike. It was Fire's version of Shrapmetal and would have served as a good attack spell for Light side Sorcerers.
The light side Cleric doesn't have any good offensive spells, except maybe Spirit Lash.
Dark Side is pretty easy. The only thing I hate are the Wizards that cast Dispel Magic. Extremely troublesome recasting all the buffs.
About Archers, I find that they don't really shine in 7 as there are Blasters/Rifles for ranged combat.