The first iPhone was the opposite of vertical integration. BOM was the same HW parts Nokia, Ericsson and the rest had access to. Samsung ARM SoC, Qualcomm modem, SK NAND, Sharp LCD, basic stuff. Apple had the OS, UX, SW and stuff like full feature HTML browser down to the T in ways that made Nokia and the rest feel like dinosaurs.
Symbian wasn't designed for low latency input, and the entire S60 app ecosystem on top of it was designed for button-control.
The whole attempt of Nokia to somehow transform S60 into a iOS competitor was visible in the Nokia 5800. It was the best possible solution to somehow bring the S60 apps to a touch interface, and it was terrible.
Not terrible because they cut cost, but because the foundation was wrong.
In my observervation, Nokia also didn't adapt because of cost-cutting. Like all vendors at that time, they didn't believe that the consumer would be willing to sacrifice
1. Battery runtime
2. Durability
3. Tactile user-input
just for a slim, fashionable and snappy Device.
For years after the iPhone, they tried to answer it while preserving those 3 aspects. Don't add a stronger CPU, don't add glass but higher quality plastic, find a solution to have buttons AND a large screen.
Always building a phone, while Apple built a pocket computer.
That said, Apple was incredibly lucky that the early jailbreak and App-hacking community forced them to create an App store.
Noone had a Linux-based consumer OS with 3rd party apps, because it was wasteful for a phone. Suddenly the iPhone became a Smartphone, and there was no OS on the market to match it.
Nokia's real problem was that they didn't have anything to counter the Galaxy S series which was the benchmark in the Android world for many years, so they lost the high-end market by mid-2010 and as Android phones got cheaper they lost the low-end not long after.
Do you have a source for this? I think phone manufacturers prefer whatever sells best, has lowest cost and highest margins, preferably all at once.
And compared to Android, Symbian lagged on all those fronts. At its origins it was still a low-level embedded OS that was forced to mutate into an app-based OS and it showed in UX sluggishness, the convoluted soruce-code, dated build toolchain that took days to compile, and in the lack of cheap and easy ways for indie devs to develop and ship apps to consumers. By the time Symbian opened its source code and app build tools it was too late to compete with Android and iOS.
They tried to persuade us to use Qt to write apps (as alternative to iOS)... and they haven't shipped a single phone with Qt available as toolkit. They told us they might ship an update for N95 and perhaps one other model to pre install the library. At the time when they had literally hundreds of models.
When we finally put an app on their store, they failed to approve it in 6 months (!). Apparently because we chose the whole Europe as launch target so each country's Nokia office had to approve it separately. Silly us.
Afterwards we moved to Android (1.5, with 1.6 coming) and iPhoneOS.