Over all the codex suffers from Codex creep. So as armies get updated points tend to go down.  That being said, I don’t think that Guardians in particular should be dropping in points.  The idea of Guardians dropping to 6 points like an Ork Boy seems wrong to me.  Orks are numerous and fight in large groups.  This seems to be at odds with the idea that the Eldar are a dying race.  (At the same time, having Ork boys being 2 points cheaper than a Guardian as things currently stand seems pretty bad) I personally think that Guardians should probably move more towards being a bit more durable and pumping out punishing firepower at range.  I think that Fire Warriors in the Tau list are more along the lines of how Guardians should be. 4+ save with a good ranged weapon.  Of course having the shuriken catapult as a lower strength than the Pulse Rifle, but with the addition of heavy weapon support would make the unit different from a game point of view.

I also find that the codex lacks synergy in many areas. Most assault troops in the codex lack things like assault grenades and assault transports to help them make it into combat.

In general all of the upgrades for units are focused on a single model, like an Exarch or Warlock.  In particular, Exarchs seem to fulfill the roll of a veteran sergeant and that of a buffing character and/or wargear upgrade.  This bundles a lot of points into one single wound model.  In other armies a unit can have a sergeant type, a heavy weapon type, a standard bearer type and even an independent character like a Sanguinary Priest, or you can pay points per model for a particular bonus or add on.  With Aspect warriors though it is the Exarch that can buy the weapon upgrade and the two squad abilities and he has the higher Ld score.  Even an Autarch joining a squad of aspect warriors is relying on the Exarch being alive to embue the abilities on the Autarch and the squad.

I think that with a little effort the FAQ for the Eldar codex could help them out a bit more without even altering points values by:

Fixing things like pointless Exarch abilities

Tweaking unit wargear, like adding plasma grenades to Guardians and Shining Spears

Altering the range or statline of the Shuriken Catalpult :

Perhaps for standard catapults

Assault 2 Range 12 inches or Heavy 2 Range 24 inches

and for Dire Avengers make it

Assault 2 Range 18 inches or Heavy 2 Range 30 inches

Alter vehicle upgrades to better reflect the changes in 6th edition

For example: Change holofields to give the vehicle an improved cover save.

Finally, Eldar could really do with a flyer or at least some sort of anti flyer weaponry.