I think it is perfectly fine to equip with the cable even if you dont intent to actually tune or change anything. It is a great maintenance and diagnosing tool.
If you look at romraider forum you will find detailed explanation of what to install, how it works, and what to log. There is also different explanations depending if you want to only datalog or actually tune. I read the part for datalog and diagnosing and I thing it is a great tool to be able to do the basic. Then when you have an issue and someone asks if you have a datalog you can say yes and post the information and get better help.
Resetting the ecu will clear the check engine light, but if your issue is still there (which is likely if you didnt do any change to the car) the check engine will come back.