Most people aren't going to deny that RuneScape combat could use some work. As it is, a fast offensive melee weapon and acceptable armor is all that it takes to succeed. For the rare times where you need magic, Storm of Armadyl (if you have money to burn) or the Polypore Staff (everyone else) are the go-to choices. Ranged is generally only used for its armor and for the handful of bosses that are both dangerous up close and resist magic, or if you can't afford to use magic (which is bound to be the case for a considerable portion of players). There are, of course, exceptions, but that's a topic for another article. This one is for listing a few general potential changes that could be made. Not the specifics. Those are for the people who have the numbers. I'm not one of them, nor am I an elite player, so I'm bound to get things wrong.
The first step is defense. To put it bluntly, the average player is going to need it less than his other stats unless he's involved in clan wars. It's why players choose Bandos armor over the much sturdier barrows sets. If you're on a Slayer task, the other monster isn't going to hit you very often with either set, or it's going to hit you often enough that you might as well use prayer regardless of your equipment. Long story short, the average player is going to choose 6 strength over roughly 60 defense. Similarly, players will choose a defender over a shield with more than double the defense; the substantial offensive bonus is much more valuable.
Jagex attempted to solve this problem with damage soaking. While it has its uses, it is limited by the fact that you have to take more than 200 damage for damage to be soaked. In player-versus-monster combat, that isn't going to happen often. If it does, chances are you should have been praying or you're fighting a boss. Even then, the amount of damage that your armor will absorb is negligible, unless you're using the Ganodermic set. The big change should be for armor to actually make a difference. Life point boosting equipment is a step in the right direction, but the only equipment with that benefit is restricted to elite players. Even rune armor could provide a boost, but not so much as Torva.
Monsters' stats would have to be adjusted as well. A player on a slayer task would have to make a conscious choice between equipment sets for the average monster; Get the task done quickly but pay more for supplies in the offensive set or settle for a slower task and reduced (direct) costs in the more defensive set. Naturally, there would still be monsters that you could breeze through with weaker armor and monsters that you would need prayer for, but these would be less common than they are now, or dependent on the player's levels: Higher level players would, as always, be able to get away with a lot more as far as equipment goes.
As with any other large overhaul, the change relies on Jagex being able to foresee the ways in which this would affect virtually every other aspect of combat [laugh track]. They can't rebalance defense without rebalancing offense, which they can't do without rebalancing monsters, and so on. It can't be left half-done, or you'll end up with another damage soaking upgrade - that is, you'll end up with a quick fix that is shockingly effective on the one enemy that is affected by it. It's better than nothing, of course, but not by much.