Runewords should go more in D2 direction.
Runewords should span across legendary and ancient legendary in power scale. Low easy runewords for mid-game is great aswell, like for exemple a stealth or ral ort tal shield i believe it was. Spirit was a bit too powerful in regards to which runes it needed.
2. Very important. As u said. It makes white and eth items and sockets interesting. Not just salvage or crap u dont pickup. Runewords was great although some were too overpowered. So runewords should be similar to legendaries its just a different and enjoyable Journey and crafting experience..
And finally, dont give us the exakt list. Let the players find small Clues to try and figure out what runewords exist. Will make launch more interesting 
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amen
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Yea, pretty much exactly my feelings.
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As a D2 fan, the "runeword" system that they have so far in D4 is not what I think of when I think of runewords. It reminds me of PoE gems or "skill runes" in D3. I don't like that they're using the name because it feels like a cheap way to draw on the nostalgia without delivering what people remember in terms of the runewords from D2.
Finding item bases (ethereal/superior with/without sockets etc.) was extremely exciting in D2 because of the crazy endgame runewords. Finding runes was also extremely exciting for the same reason. Crafting runewords with these items was also very exciting for me as a form of endgame content. Acquiring the items necessary to trade for said runes contributed to hundreds of hours of game play time for me throughout my teens -- and would likely still today.
To be clear -- Having a system by which you are able to modify the way you play your character (through skill modification), I find very compelling, and it should exist independent of what I understand to be runewords, in my opinion.
That being said, runewords as they existed in D2 were more of a form of end-game crafting, even though the runewords themselves also sometimes dramatically changed how you played the game.
Specifically, I really liked that finding a Vex/Ohm/Ber rune meant something huge. It didn't mean that you could now get a chosen effect when you drink a potion in a 2 socket item. It meant you could participate in meaningful end-game "crafting," by making runewords that could dramatically change how you play the game. It also felt way better than finding crafting materials in D3 -- no comparison.
TL;DR
(Good Job Blizzard) D4 should have a way to modify how your skills work (like the current implementation of "runewords") -- but they aren't runewords as far as I'm concerned.
D2 runewords consisted of acquiring extremely rare materials for end-game "crafting." -- There are many pieces that have to come together to get a good runeword -- let alone the RNG elements to the rolling itself.
(Please address this Blizzard) Even if D4 sticks with the same system for modifying items and calls them "runewords" -- which I really don't like -- They should have a way to craft end-game items, which would be the true sucessor to D2 runewords.
How do people feel about end-game crafting and the use of runewords for the skillmodifiers we saw in the announce?