Hm, but that's just your own type of "definition".
Nah, the underlying mechanism is not "realtime" for sure.
By realtime, it means when I press something, if I'm not in animation of doing another, it starts right away. If I moved out of attacking range while enemy attack starts, I shouldn't be hit. If I saw a long casting spell, I should be able to react and evade or counter. In IE based game you can't do any of these. That's the main reason Diablo got popular in the first place, because it only roll dice when you hit to check for miss/resist/critical, and of course drops.
Cool-down ablities and stacking of spells/attacks is not a basic requirement of real time combat games, these elements are only attemps to minimize the micromanagement while pausing.
If you try to stack another spell before all parties in the turn finished, it should either fail or only come out when next turn starts and it's your turn to action.(It's being so long, and I think BG1 should be the former, and BG2 latter.)
And no, cool-down is there for balance and to prevent you stacking, thus increase the requirement for micromanagement to keep you on your toes. If you can stack spell in say Diablo 3, kiting would be so boring you fell asleep for endless click back and forth, and only spam spell key if it runs out. And by realtime, if you stack, it should come out right after your character becomes idle or only moving, which is not the case in IE games.
In real time party games you could choose yourself which of your characters you want to give which order in the sequence you like. And in the end everyone will perform the orders simultanously and not "turn-by-turn".
Which IE games do none of these, it buffers the order, and only perform it when it comes to that character's turn. There is no simultaneous action happen in any given time of IE games, it's a given fact that all actions are based on rolls, except movement with its special condition.
The simultaneous feeling of warrior's strike and wizard spell hitting almost at the same time is an well crafted illusion. (ie. if I gave a stealth theif's attack last, or pause after I saw rolls of first attack, then issue order, it will be rolled faster then my wizard's spell. ) If you also remember that all try and true synchronized attack orders gets interrupted when you encounter fast enemies, it brought you back to the turn-based nature of IE.
And the matter you can auto pause on your turn or each round is further proof that it's more turn-based than you would like to believe.
I think this system goes so far all the way to even NeverWinter Nights, which is closer to true hybrid of realtime and turn-based in my opinion. After NWN, RPGs departs to turn-based, Final Fantasy style turn-based(with action bar to fill), BioWare(true RTwP) style after NWN, and hack'n'slash.
There are just my opinions, and you may say to be able to play in realtime makes a game realtime in your definition. And I think it is possible to do a mod to enable this type of play, if this part of engine(roll/action) is exposed in the script part of a mod.
