Everyone receives crit from agility. It's just at a different rate. In fact, according to wowwiki's article, plate wearers get crit from agi faster than rogues do.

For right now plate wearer's receive crit from agility but after patch 4.2, that will no longer be the case. All plate wearer's will no longer receive any benefit from agility items. This was done to enforce and put more of a separation in gear. Meaning plate wearers should stick with str/stam items where mail and leather wearers (if the spec/class needs it) should stick with agility on their gear. They are even putting a new pant enchant in for the plate wearing tanks, so they have an option.

Actually that is somewhat interesting to me now that you mention it. Agi classes get crit from agi and int classes get crit from int. The trend is bucked with strength users.

This is just my immediate reaction of course, I'm sure someone else can provide a real answer to your question, and I'm sure there's probably a logical explanation somewhere that I'm just not thinking of right now.

I would have to say that's just how the stat was made to work. I don't really believe there is any rhyme or reason for it aside from the fact that in most if not all RPGs or anything, Strength has always been a stat that increases damage and sometimes health and Agility would increase the chance to dodge, increase crit chance, and for certain classes give damage.

Currently, every class receives crit from agility. The specific rate depends entirely on class, and isn't really related to what type of armor you use.

As of 4.2, every class receives crit from agility. The specific rate depends entirely on class, and isn't really related to what type of armor you use.

The only thing changing for plate wearers is they will no longer receive dodge chance from agility.

From the patch notes:
"Death knights, paladins, and warriors no longer receive any bonus to their chance to dodge from Agility. Their base chance to dodge is now a fixed 5%."

I think this is largely due to how stats worked in Vanilla.

From what I remember, Int used to give mana and crit, without offering spellpower, and Agility used to give 1 AP and a decent chunk of crit, whereas Strength was (for the primary stat-users like warriors and paladins) giving 2 AP.

Now that it's no longer the case and agility users are getting the obviously superior primary stat scaling, you can see that it's common for plate-wearers to see modifiers in damage done to compensate.

Personally, it makes sense to have agility provide passive haste and strength to provide critical strike, but.... I'm sure lots of people would disagree.

Can't you see the logic behind it? You get physical crit from agility because you are "agile". You get caster crit from intellect because.... where else would get it from? Now why should you get crit from strength? It'd be physical crit, but we already get that from agility. It makes you hit harder with your regular hits though.

By the same logic, being agile can also mean you're quick - hence why it would make sense to give haste.

As for strength giving crit, the harder you hit, the more likely you'll shatter the enemy's defense. Isn't that essentially what a critical strike is? An attack hitting extra hard?

It's because if you were critting with all your abilities as a str user then you would be doing EXTREMELY high end dmg. Not only that but as a Str dps user you get talents that increase your crit for a few abilities to roughly the same amount as a geared agility user i.e Killing machine (which auto crits), rule of law, sanctified wrath, Impale, cruelty, rampage, and Incite (which also causes auto crits). Soooo yeah you guys hit hard enough to not really need crit rating from your str

1. I never said that Strength users should autocrit.
2. If you assume that they will keep the AP coefficients of the abilities IF this change makes it live (Which is EXTREMELY unlikely), then there's something very, very wrong with that thought process. This wasn't a plea for a buff, but merely a statement.

Zelcor don't even bother to defend it or rationalise it. Plate DPS used to want Str and Agi and their gear had it both, in Wrath and BC the benefit for Plate wearers to stack Agi instead of Str saw them wearing Rogue leather which just had Agi and AP.

This lead to the reform in Cata where you get a 5% bonus for wearing your class armor type to stop this kind of shenanigans (and IIRC they also fixed the issue with the amount of armor a piece had coming from the item budget, which was why leather gave more DPS then Plate).

On a similar note Enhance shamans and Feral druids used to benefit a lot from Str, but that is being nerfed in 4.2 as well. The stats are still in transition from Vanilla design to Cata design, all the oddness is due to that.