A lot of ARPG in this subgenre involve itemizing for movement speed. Damage makes dungeons and clear times faster, movement speed just as much. Kill faster, move faster. There’s also the mild argument of being defensively useful (you can avoid and move out of bad faster).
You are out a legendary aspect, yes, but the only offensive effects you can get for a boot’s aspect (for sorc) are Lucky Hit Chance while barrier (which can go on helm instead), Damage to chilled increase from Penitent, and these Esu’s Heirloom.
These definitely aren’t all that exciting to me, but providing offense that boots normally can’t do. That definitely makes them unique and useful in their own right.
And for the sake of being complete: if you’re playing a build that uses teleport or crackling energy to do damage, then there is also an argument for +ranks to teleport or +crackling energy damage as an offensive option. +Flame shield ranks technically also improve damage, but that’s unlikely to be considered an offensive option by most.