Ok so I found the culprit. Apparently I need to choose the second or third option for the Data Storage. Even though I've checked the 'Store Data Locally' property of the fields, that is valid for DCR only, not DECS.
When I said the fields and their values are in the document property, actually those info are lively pulled from the Oracle WHILE THE VIRTUAL FIELDS ACTIVITY IS ACTIVE. If I stop the Virtual Field Activity, then none of the documents' document's property contains those fields and values. My mistake for thinking those are Notes data because they seem so real (with correct field names, SUMMARY and all).
But still it beats the purpose of DECS if you need to have the data in Notes in order to have them displayed in the view.
To @RichardSchwartz, thanks for at least providing some directions regarding the SUMMARY thing. Never knew about that.