Soliciting opinions on a house rule

Alraune, a frequent CharOp poster on the old WotC boards, once posted a list of house rules from a home game, which included this:

Enhancement Bonuses: The enhancement bonus of the weapon or implement used for an attack is added to its damage roll once for each die of damage in the base roll. This rule applies only to the damage dice listed in the power itself, not dice added by outside sources such as class features, items, feats, or paragon path features. This change is intended to help narrow the disparity between attack powers which deal small rolls of damage multiple times and those which deal a large amount of damage at once.

What are your thoughts on this rule? As stated, the idea here is to even the power curve between multitap powers (the CharOp go-tos, like Rain of Blows, Flame Spiral, etc.) and multidice but single tap powers. Does this up the baseline damage of all PCs too much in an attempt to level the playing field with multitap powers? Is such a change superfluous in a game without overreliance on multitap powers? Does this open up some otherwise solid PPs for greater consideration along with Demonskin Adept and similar PPs? Etc.

Anyway, I'm turning this over in my mind as more of a though experiment than anything else....

I'd only do something like that if you then reined in other stacking bonuses. i.e. something like this:
All bonuses from source X are bonuses of type X. Have two feats that add a damage bonus? They're both feat bonuses. Have +3 Frost sword, +3 Cold Dragon Shard, Iron Armbands +4 and +2 damage bonus from gloves? Total bonus is +4 because Armbands.
Options that give bonuses from Class+Paragon+Race are power bonuses.
Vulnerability is instead a bonus. So Lasting Frost is a +5 feat bonus to damage once Vulnerability is established.
Anything that even hints of being extra damage is extra damage.
Use Inherent Bonuses to provide 'Enhancement Bonuses'

Then give all the bonuses per die except enhancement+stat. This both stops a lot of the OP abuse and boosts the big W attacks. So the 5W attack gets +20 from Armbands, but he could also get +20 from having a +4 Sword. Etc...But because the PC is say 16th level, each attack gets +4 per attack. So a 1w+1w+1w attack might only get +24 damage from feat+item, but will also get +10 per attack from stat+enhancement(+30) for a total of +54. Where the 5w attack will also get the +10 per attack from stat+enhancement(sad +10), but will instead get +40 from the boost for a total of +50.

So that big 5W daily power is now 5w+50, which is better than the 1W+1W+1W of Rain of Blows, which is only effectively 3w+36.

Looking through the math like this is super, super helpful. Thanks!

Agree with MwaO. I always thought 4e should have doubled down on its 'bonus types' rule to be really strict about. Every bonus is typed to its, er, type. Period. No exceptions.

Then you can go back and do fun stuff like let 'item' bonuses apply to each die of damage as proposed.