It's not just age, it's a sense of loss. I can still go down to the store and buy milk in bag form, just as I could when I was a kid, so I don't feel nostalgic about it even though it's old. I feel nostalgic about the web of my youth because that place is gone now and it'll likely never come back.
In tech circles we like to obsess over new technologies and all of the amazing new possibilities they've brought. We don't spend nearly as much time talking about all we've lost.
I also don't find that new smartphones have much touch-based interface latency; but even so, that kind of latency doesn't have anything to do with the internet, nor the halcyon days of late 1998. To my recollection browsing the web in the late 90s was far more exciting but also far less useful than today.
The modern internet has a lot of inefficiency, but I don't see how you could seriously claim it's slower than what we had 20 years ago. Sometimes heavy web applications are relatively slow because they're underoptimized, but that's less of a technology failing and more of a developer failing. Most websites load spectacularly faster, and perform better, than all but completely static HTML websites from two decades ago despite having much larger byte footprints.
Some websites overloaded the 98 web by being an entire page of diced and sliced graphics that assembled the page. Most were mainly text and appeared pretty much instantaneously. Images came slower than the article you could be already reading if you were on dial up.
One of the things I dislike about the current web, is how slow most sites have become - mostly thanks to an absurd overhead of JS and third party SaaS just to display a text article with a few pictures. The number of sites that will unreadbly bounce the content around as various web fonts, icon fonts and other trivia load is pretty ridiculous. It's the main reason I now browse with JS off and white list JS for a tiny few.
Douglas Adams expressed this well:
“I've come up with a set of rules that describe our reactions to technologies:
1. Anything that is in the world when you’re born is normal and ordinary and is just a natural part of the way the world works.
2. Anything that's invented between when you’re fifteen and thirty-five is new and exciting and revolutionary and you can probably get a career in it.
3. Anything invented after you're thirty-five is against the natural order of things.”
For me the stage that came after this is, "Well, change is going to happen, so either I need to get off the merry-go-round or I need to learn to like it." Geocities and FTP clients are as dead as fan-fold, green-and-white line printer paper, and for the same reason: we found better ways to serve the same needs.
Justifying one's nostalgia by pining for the days of 14.4 kbps modems doesn't make a lot of sense. If they were good, then surely my first modem, a 300-baud acoustic coupler was better. Although I feel a tug of nostalgia when I see one, it wasn't better. Optimizing to save a resource we have in abundance makes as much sense as depression-era grandparents saving bits of string for possible reuse. It wastes that most precious of non-renewable resources: your time.