Well it totally depends on how rare these items will be. If they come in the form of tiers like (think common, uncommon, rare ect)
Tier 1 - effects 1 attribute, no other enchants
Tier 2 - effect 1 attribute, 2 enchants
Tier 3 - effects 2 attributes, 2 enchants
Ect ect
Then I agree, not all of them should be 'soul bound'. If they come on the form of just 1 tier that affect multiple attributes and are extremely rare. Then I disagree. All depends on how they are implemented
Note; could even have something down the lines of 'soul bound' being a rare enchant/ effect on these items (all tiers could get it regardless but there's a low chance maybe?)