Diablo III: Reaper of Souls

I think people underestimate how complex and shitty the runeword system was. There were literally billions of possibilities, and at one point, some where unknown. The rarity of anything above Gul makes Legendaries in RoS look like blues.

I think maybe adding a few more sockets to different slots and having Legendary and Set gems would suffice. They'd perform identically to what a runeword implementation would, without the added complexity of combining complex or large sets and adding large number of sockets.

Yes, it was very complex. It also made some specs completely broken. I'm pretty sure I've obtained at least 1 of every single rune within my time of playing d2 but ya anything past gul was extremely rare.
Most runewords were actually not that bad either, if you consulted any sites that actually had the order listed ._.
Let's see off the top of my head the craziest ones were...

Enigma - durr insane str increase to make str bugging your equips easy, damage reduction + that +1 to teleport made summon builds so good.

Faith - Fanaticsm on a bowzon! Never had I had so much fun hitting the speed cap. Sub 2 min hell chaos clears was a blast.

Ice- I think this one could lag the game completely since it proc'd frost novas and a stupid % rate.

Bramble- must have for any poison builds.

Chains of Honor - great armor all around.

Fortitude - So I heard you like to deal moar damages? 300% more on an armor derrrr.

Infinity - Conviction aura that basically helped break those annoying immunites in hell. The defense reduction made it better than pride for a skellymancer.

Pride - Want concentration/might/ on a merc?

stealth - You're low level go to rune word that was fairly easy to make.

Heart of the Oak - Amazing caster runeword. Provided everything you could possibly want.

Call to arms - Decent replacement to a barb's battle orders.

Grief - Stupidly op on a smiteadin and good for any other melee class.

breath of the dying - powerful melee runeword

last wish - even stronger than grief , but good luck with the runes.

There were so many good ones out there and the best ones replaced uniqes in nearly all cases. They were easily accessible though because of the rampant duping that went on in that game though.

Don't forget jewels either, those became pretty crazy.

Aside from that I honestly think they should either put a socket in every weapon or just not allow it at all since if you find one without a socket it's basically trash anyways...