Players weren't choosing IAS because it was too powerful, they were choosing it because nearly every other offensive affix in the game is incredibly underpowered. Not only that, but there is a complete lack of variety and availability of both offensive and defensive affixes. Players wouldn't have been forced to choose IAS if there had been a number of suitable alternatives. This answer is so simple, I'm really not sure why this hasn't been addressed.
Obviously Blizzard doesn't believe that buffing everything else was a viable solution because that would be admitting to a major failure in testing and design on their part(I'm not claiming that this was the ONLY reason). It became much easier to remedy the situation by simply nerfing the anomaly. It is clear to me that this issue was not given NEARLY enough thought on Blizzard's part. They heard hoofbeats and thought horses.
What was the result? A massive tremor in the economy, slower and less fun gameplay, and a large portion of the playerbase losing their ability to trust the decisions that Blizzard makes in regards to the design of this game. Attacking fast is incredibly fun. The fact that it was causing bugs should have had absolutely zero influence on the situation. I can't imagine that Blizzard is incapable of fixing said bugs.
I am a reasonable individual, and I am able to evaluate and analyze the pros and cons of a situation. I can say with absolute certainty that the IAS nerf did NOT make the game more fun. In fact, I don't know a single person who feels that way. It actually had the exact opposite effect. The desired result was achieved, but fun was not derived from that result as it could have been.
We can't deny that Blizzard's decision to nerf IAS resulted in a massive increase in build/item diversity. However, the exact same result could have been achieved without ANY of the negative consequences would they have increased other stats instead of nerfing the fun one. Not only that, but we would have been left with an item system that was one step closer to what it should be. As it stands now, items are still grossly underpowered and most affix maximum's are FAR too low to make the affix worth acquiring.
Creating builds around certain affixes should not require the stacking of high rolls of that affix on EVERY SINGLE ARMOR SLOT that it can appear on in order to be effective. This system severely limits item-oriented build diversity. This is the current system we are playing on, with very few exceptions. Can anyone argue against this?
Bring IAS back to what it was and carefully buff the crap out of other stats. Players want to see items with absurd amounts of a certain affix. When you find such an item, you won't have to sell/DE it like 99% of the items everyone is finding. Instead, you can utilize what would have normally been a useless item, and build a spec around it. Imagine finding one piece of gear with 1600 life regen per second. Sure it's powerful, but that is what the game is about! How about an item with 12000 thorns damage? Or an item with +18% chance to stun on hit. These are the kinds of things that make an item hunt interesting. I'm not saying that such items should be common place, but I am definitely saying that they should exist.
I really can't give enough examples as to why this system would make the game infinitely more fun. Say you find a monk weapon with 900 intelligence. Obviously this wouldn't be as cool as a monk weapon with 900 dexterity, but then you realize that 900 int is ALSO 90 to all resists! What would have been a useless weapon could now actually be utilized in an interesting way. So now you can use this weapon and swap out that other piece of boring all resist gear for something else that is interesting!
Say you find a Barbarian belt with +86 maximum fury. Maybe you could try an execute style weapon throw build? Sure it might result in the desire to play some crazy OP whirlwind build, but it doesn't FORCE you to do so. It GIVES players the option to try something that would have otherwise been impossible.
Say you find a demon hunter cloak with +28% increased spike trap damage and +17% block chance. Maybe you can finally try that spike trap tank build you dreamed of?
The possibilities are endless.
Obviously you can't have a game where a huge chunk of the items are grossly overpowered and the game becomes a cakewalk with only minimal farming required. However, you also can't have a game that is nearly devoid of excitement in regards to the item hunt and item-oriented build experimentation. Start by increasing min/max affix values on MANY of the current stats, then finish by giving items a chance to roll VERY high values of an affix. THESE are the items that people would kill for. THESE are the items that make the hunt worth the effort. THESE are the items that make people squeal when they see them! Don't restrict this feeling to legendary/set items (post 1.04 of course). The fact that the current item system could literally force someone to farm for years before they find a perfectly rolled item that really isn't THAT great, is NOT fun! :(
Blizzard, you are literally choking the brilliant rune system you have created by placing severe limitations on the affix pool and their respective min/max values. Give players the opportunity to find interesting items. What would I do if I found an item with 400 vitality and 12% melee damage reduction? I would consider altering my build to make use of it, regardless of my class! You say this item would be too powerful on a tank class? I say that a tank class with such items should be INVINCIBLE! That is what makes tanking fun! Tanking with good gear and a purely defensive spec shouldn't feel like you are just barely able to survive the harder elite packs, it should feel like you are laughing at their pitiful attempts to hurt you!
Please consider what I have said Blizzard. I don't claim to be infallible on this matter, but I have yet to see a good, or any, reason as to why I could be.