My issue with all these ideas is that they'd be useful in all kinds of situations unrelated to salvaging. The salvage rig is a special tool you whip out when you go on a deep space adventure, looking for abandoned stations and such, not something you always want in your fleet. Of course that could be changed, but that would take fleet positions away from ships that are fun to actively use.
Some SR buffs that would help with exploration:
- SRs reduce the supply cost of being over cargo/fuel capacity. Presumably, they are very useful when attaching extra storage containers to ship hulls.
- SRs have the ability to generate supplies or heavy machinery from salvaged plunder (like metals, household wares, food). The conversion rate is pretty bad though, so it's only a good option if you are stuck far away from any harbor. Or if you just need those 5 extra machines to perform that salvage operation...
- Maybe SRs have the ability to construct simple weapons (light mg, light mortar, mining laser) to equip salvaged ships in the absence of any serious weaponry