>> In D&D an ideal four member party consists of Two melee strong characters, a healer and a spell caster. <<
I think this is a incorrect premise. I know plenty of power gamers that would disagree with this statement. In fact, spell casters tend to be the most overpowered classes in any DnD game. While it is true that many boss fights can be made easier by having a couple of tank characters in the lead, I haven't ever had a situation where good tactics couldn't change the odds significantly if played correctly. Spell casters using grease, sleep or web spells can significantly change the odds in any battle allowing other characters advantage against them. I'm using a sorcerer as my main character and have used a party of Gale, Laezel and Asterion for a number of tough fights in the game and have yet to lose a single battle and most have been pretty easy. That said, I'm now headed into the underdark and I've swapped out Gale for Shadowheart because she can work more as a front line character as well as offer party buffs. This is my 7th or 8th play through and I've used all available companions for every fight and haven't encountered one that I couldn't beat if I used the environment, magic and tactics correctly.
If your style of DnD is basically run at the enemy and beat them on the head and don't take advantage of the edge that magic can give, then the issue is your play style not the game.
JMO YMMV.
