Dialogue and story were the most important for me. Character customization, less so. Look at Baldur's Gate II, often cited as one of the greatest CRPG's of all time. You could customize the colour of you character's clothes and hair, and choose a pre-recorded voice, and, apart from assigning your 6 statistics and a handful of weapon proficiencies, that was it. Minimal customization, but a complex and original story combined with interesting NPCs and masterful dialogue. It certainly drew me into the world, more than any other RPG save for Morrowind (Chrono Trigger is up there too).

Character based skill success; (meaning a weighted % chance of success).
Core aspect of an RPG
Dice rolls ftw

See DA:2 skinnerism behavioural science at its best / worst.
Games like BG, Torment, Arcanum, fallout, DA:O and TeS even, allowed this but made it possible that you did not have to.
Even if you entered every fight you could create very pacifist builds, whether it was sneaky builds, healers, mind controllers.. etc.
Choices were allowed and skills across the board made as useful as the next in certain circumstances.

More and more RPG's are boiling down to levels, xp and loot.. to gain this you power game and pick the most destructive build you can everytime.
Variations and choices are made for you before you even start to think about what you wish to create.

In BG the amount of druid builds I made was unbelieveable, not the strongest character type far from it.
But with thought and creativity they could do more in certain fights than any other class I played.

In DA:2 there are some very powerful talents to game with, but the choice is made for you as those not on the list are ineffective.
So to play you find yourself taking the same build otherwise it becomes untenable to carry on.
This is just the game aspect of rpg's, but the freedom of choice and knowing those choices matter is important to me.