From my perspective, mobile gaming "caught on" around the time the first iPhone was released around 7 years ago.
There was already a big market for it on Symbian and J2ME, but the quirks of those platforms, and the relative difficulty in publishing and getting payed stopped it from really taking off.
Finally there was a performant platform that was easy to get started with and easy to publish for, and you could reach the _whole_ market with just a single build, and most of those people already had their credit card attached to their itunes account, so they where only a click and a password away from paying you for your work, so a lot more people could do it as an actual living.
I obviously like mobile gaming, I think the limitations are interesting, and that the input methods open doors to new ways to game.
It's not the same as PC and console gaming, and probably never will be. But that is mainly because of how and when people tend to play mobile games, not because developers are lazy
Although be careful - iphone 7 years ago couldn't even run apps, so that isn't true Apple got a lot more developer support when it could and it's easy to think the payment advantage as helping, but then they got that extra developer support long after other platform owners started up their application payment sites, so it wasn't really that (I still see companies support the minority of iphone users ignoring even the 80% of Android users, though it's getting better). Perhaps it was more that the media gave ridiculous amounts of hype to Apple whilst ignoring everything else. Perhaps it was more that iphones were newer to the US market which seemed to have much poorer mobile technology, and many software companies are based in the US. Who knows. I'm not sure what you mean about a single build for the whole market - there was an advantage of only having one model to develop for, but the downside of that is problems as more models are released and technology is improved - indeed, with loads of IOS devices, of multiple different sizes, multiple different resolutions and aspect ratios no longer applies, and it's worse as the platform started out with the expectation that there would only be "one thing to code for" - you're better off with either breaking compatibility every few years (consoles) or always supporting a range of devices (just about every operating system out there, mobile or not).
Mobile gaming, like most things in technology, is something that's grown with time, with many companies and products contributing, and there are many different perspectives. From my perspective my first experience with mobile games was in 2005 with my Motorola phone, though I didn't get into development until 2010 with Nokia/Symbian using Qt. I wouldn't say I really care for mobile phone games at all though, preferring to play on my laptop, or very occasionally my Nexus 7.
There are a lot more people running mobile games today than in 2007, so there's been vast growth since then (most of which coming from Android phones). Before there was Symbian and especially J2ME. Even before that though in the 1990s we had mobile consoles like the Gameboy (which was harder/impossible for indie developers to develop for, but then this thread was about the demand for games, not who can write them).
I've got a game programming book where a "history of gaming" section lists mobile gaming as the penultimate section. This book was published in 2003.