Reasoning: As it is right now, IAS on weapons is only 50% effective when dual wielding compared to single wielding (i.e. I need to get two IAS rolls in order to maintain my RF Breakpoint).
This change would make an otherwise undesirable hand crossbow a very compelling option even with its low DPS, and/or buff dual wielding in general.
Some additional thoughts from a dual wielder:
In examining weapon DPS affixes, the dual wielder needs to divide them into two groups, we'll call them Group A and Group B. Group A consists of those affixes that affect only one crossbow, while Group B affixes affect the damage of both crossbows. Affixes in Group A are: +Min Max/elemental damage, +damage %, and IAS. Affixes in Group B are: CHD, Dex, and Socket (more CHD).
Note: The intrepid Dual Wielder would be wise to maximize the affixes in Group B as they modify the damage output of both bows.
Going further, any good weapon needs to have both min max damage and damage % affixes, thus the dual wielder already has, at minimum, 4 affixes that are only active 50% Of the time. Adding IAS to the mix increases that number to 6. How many affixes do single wielders have that are only active 50% Of the time?