A lot of misunderstood here. Maybe I will clarify some things. Orbs "always" (at least when I remeber, so I suppose from orb introduction) dealt dmg and it was pure force dmg. Same passive shield bash worked "always" with orbs from feat and vanguard enhancements.
Orbs natively provide a bonus to Elemental Resistances when blocking
..but its flat bonus and it's not enough for heroic tho. Percentage absorbtion is much better for big dmg numbers. In te other hand flat bonus to saves is nice.
Orbs are not Shields, though, any more than Runearms are. They're mainly conduits for spellcasters to focus their magical energies...I dont see the logic in them providing significant defensive benefits just because you hold them up in front of you.
As said orbs had passive bash from begining (worked with Improved Shield Bash feat) so they are mentoined to be some kind of shield too, and this force shield animation showing when bashing make that feel too.
Especially when there's many mechanics in the game to allow spellcasters to use actual shields in their offhands...making Orbs into de facto Shields dilutes the utility of things like EK and ASF reduction
This change will not make Orb like Shields especially in defense capabilities. Not even close. Shields have passive bonus to prr and mrr orbs not. Shields can be futher improved with Shield Mastery line, orbs not. Shields (heavy/tower) gives you passively something similar to improved evasion - spells with reflex save deal half dmg when you wield one of those, orbs not.
On top of that consider that I proposed feat and I consider feat requirement as a hardest sacrafice to get something. You got only 7 avalible feats when you count basic, heroic leveling only. So taking this feat is quite costly I would say, especlay if you copare it to 80 AP avalible.
In my opinion this proposal won't change much for Eldrich Knights. Heavy shields will be still better for them if build is not focused around evasion (heavy/tower shields block evasion). Other thing is that EK needs a bit refresh. I never understood how it was designed - give ability to use int or charisma to hit with shield, but not dmg. So let EK be albe to hit with shield but deal almost no dmg... Why? Who's idea it was? Designer, can you speak?