The first iPhone didn't have GPS either. No iPods had speakers back then so that wasn't missed, you just used your earbuds. It was great for browsing the web and media consumption, since you either had WiFi or you didn't (no slow Edge network to tease you). Once the App store came out you had Instapaper for offline reading, and Google Voice for messaging/calls.
You're right. The first iPhone did not have GPS. But it did have the connectivity to make other geolocation services useful, at least in a "Where the fuck am I at?" sense. (And the iPod Touch also had wifi-based geolocation services that were spooky-good, if it was online somehow.)
But from various PalmOS devices to whatever Android device is in my pocket right now, carrying wired headphones has never been a thing for me for whatever reason.
So as a Google Voice user since it was still called GrandCentral, having Google Voice available on a Wifi-connected touchscreen pocket music player called an iPod Touch was simply never very useful to me: The OG iPod Touch was lousy as a telephone, since it lacked all of the basic parts (like a microphone or an earpiece) that made telephones useful, and SMS was not yet in its heyday back then either.
I got much better use of the service with my dumb phone with T9 text input and transcription of voicemails to SMS, and my dumb phone worked anywhere instead of just where I could find a Wifi network.
Jailbroken, the iPod was an amazing pocket computer with a brilliant display, thin profile, and exceptional responsiveness to touch input, especially with third-party apps and improvements installed. It was fun having a real *nix userland installed on it, and it sure seemed novel to SSH from it.
By default, though? Almost useless except as a music player -- a task that previous iPods did better.
(I mostly used my OG iPod Touch to take offline notes. It did OK at this, but previously-used PalmOS devices did better in terms of input speed and portability of those notes.
Even relatively high-end aftermarket car stereos at the time were afraid of it: "Oh, why sure I can play music with your iPod!
