I fully expected the writers to go down the same route as the Wizard of Oz...
...You actually had all those attributes all along and didn't even know it.
well, that's kind of true. Data frequently showed curiosity, confusion, kindness, etc. before the chip.
Also, I think it would be impossible for a truly sentient, self-aware being to not have emotions-without them, it has no wants, so how would Data get the notion to join Starfleet, befriend Geordi, take up painting, etc.?
So Data either had at least some emotions at a basic level, or he wasn't really sentient or self-aware, he was just a very good mimic of a self-aware being.