In the early days of 2G GPRS, phones are equipped with WAP browser. Due to the slow speed, web or so-called WAP pages are stripped down and left with text and simple graphics. But these WAP pages get users excited. Developers and content owners took the opportunity to monetize the first "mobile Internet".
Later, cameras are integrated with the phones. Display is only limited to VGA and low-resolution. Either this is due to the technology of phone display, camera or speed is insufficient to carry the bigger multimedia contents.
Initially, MP3 and videos are played locally. These MB size contents are downloaded via a USB cable. Today, with the 3G and LTE speeds, you can play video (Youtube) and Music online instantly.
GPS used to be a separate device but now its s standard feature in the phones.
Nowadays, we see more and more sensors build into the phones such as Wireless Charging, NFC, Gyroscope etc.
There is no longer a need to carry so many devices to make a call, listen a music, watch video, play games, taking photos, finding direction, pay online, browse the Net etc. This is the main reason why smartphones has become part of you and you will never able to part with it.