I am not big fan of playing update on Oracle standard tables , but recently their was a question of updating the enable_flag to N for Inactive Items.
My take on it is once we Inactive item (Note - System will allow you to inactive items from the master Org only and not from Non Master Organizations), system will not allow you perform
Customer Orader Trasactions
so what is the purpose of updating the enabled_flag field. Updating column in MTL table is not a big task , but it is hard to to analyze it's Impact on other Modules.But in case you have some customization based in this field I suggest to conatct oracle and check with them.