I find myself leaning towards Rules-Light type games. One of my foremost beliefs in gaming is that if it is within the nature/sphere of the character, and it isn't too over the top, they can do it. I've never been one to haggle the rules, quoting x book or y piece of errata. The Rule of Cool, as it were.
Probably why I lean more towards a system like 7th Sea. Built around being fun, exciting and cinematic. Instead of rolling dice against a stat block, you often roll dice against each other. The roll and keep system lends itself to the gamble of the mechanics.
That being said, playing 4E often leaves me confounded. So many stats, so many different powers to keep track of, all the species and their individual quirks, be they monster or PC. And sometimes I find unnecessary complications, like the component requirement for ritual casters. Having the appropriate components, taking into account their weight and relative size inside one frail wizard's pack.
Each magic user or ritual caster is almost bound to possess several bags of holding to accommodate any quantity of ritual minutiae. And some of the minor rituals are incredibly useful, but you don't know if those specific circumstances will happen in any given game. How often does your magic user get a chance to stop in town and pick up those components, or even happen upon them growing wild?
Instead, what we've done is tie them to healing surges. My sorcerer typically stays to the back of combat, avoiding damage as only the most wily of chaos priests can do. But I still need those healing surges. And so it not only simplifies ritual use, but it makes it something precious. We can assume that the components are correct and accounted for, or the words are spoken. But it implies that it still draws from the magic users own inner reserves of Will.
I think that tweaking the rules is sometimes necessary, but only if it enhances gameplay. And that is my rather abrupt summation. Or rather, this is. I feel that in any given game, the rules should only exist to the enjoyment of the group.