It is fun to push old hardware for the wow factor and tinkering for tinkerings sake but it's also gratifying to get work done in the fashion and pace a computer was designed for.
For sure. While there are some exceptions and this doesn't necessarily apply to everyone, what's really making an impression on me now though is just how much better they are at both offline recreation and productivity in general.
Elaborating further, for games, you don't have to deal with day one updates, microtransactions, DLC, or account logins. Just go to the Garden, download a few titles, install in 2 minutes, and you're ready to go. Likewise, why bother with Office 365 or Adobe Creative Cloud with their aforementioned subscriptions, yet more account logins, and cloud storage when you can simply fire up Office 2008 or Creative Suite 4 (or older) on your classic Mac and be able to do 90% of the same things?
Even when you're trying to get work done on the modern system, most of the time you still have app notifications, automatic updates, email clients, social media, and 100+ other tabs open on the browser all simultaneously competing for your attention. Meanwhile on the classic systems, you are forced to do one thing (or two things) at a time because of their limited resources, resulting in either more engaging gameplay or produce completed faster and more efficiently because you can completely focus on what you're doing for a length of time.
They're just such cleaner environments.