How could anyone complete BG buy the expansion and then not play it? (by the way I don't think the combined set is fully patched since the hidden items are still present.)
The three disk set is fully patched. This is evident by the version number on the menu screen. What are these "hidden items" to which you refer? There are no items removed by the patches.
There are items which need you to have your cursor to be on the exact point. Walkthroughs which mention these say they are not present if you have patches installed. But you're right I didn't read what you wrote carefully enough (sorry) and thought you were refering to the six cd set.
If you are referring to the Ring Of Protection + 1, the Ring Of Wizardry, and the Ahnkeg Plate, then you are wrong. These items are not removed by any patches. They all appear in the fully patched version of Baldur's Gate.
Newcomers to BG1 and I daresay even veterans at times have problems locating well-hidden objects. If it is of any help, I have found the English Language Text Update from Baldurdash useful.