Mauricio,
Yes - major flaw in the product, in my opinion. We use process actions to vote on things (approve, reject), record notes, and then delete the results because the process logs take up so much file space. This made sense to someone? And, why is that very useful Notes tab not available on all Action Items, only process based actions? Another miss.
What we've done, where records of voting are required to be maintained, is to have the process copy the results to a read-only text attribute on the object record associated with the process. There, users can see who did what, when, without having to click on anything else. Data is there forever - process deletion doesn't affect it. And, the attribute can be easily exported to DWH for Jaspersoft reporting. This is a pretty clean workaround.
Dale