A clue for you might have been that I mentioned Project Bento. That obviously indicates I'm current on SL technologies, and not 'defending it based on memory'. I didn't mention the name of the island because it wasn't necessary and I prefer to retain my anonymity -- something you should be able to appreciate, considering how you're challenging me namelessly. People actually *in* SL know where it is. I'm on friendly terms with every other builder on this island and there isn't a single bot in play. There are times, for example, when I'm the only soul within 65,000^2 meters -- though such periods are usually brief. I logged in just now and saw there are three people on the sim right now, besides myself, including a name I don't recognize.
That's just one island consisting of loosely-associated builders/owners. There are places I visit that are almost *perpetually* active most of the day, often with dozens of avatars at the same time ... for example Builder's Brewery. Some club-owning friends host parties that draw enough avatars to max out the entire sim ... though only for an hour or two. Second Life isn't deserted, but I *do* think it's spread out far too much for the population it has. Much of the mainland expanded during the hype years, only to become lots of abandoned parcels since. A lot of social activity migrated to the thousands of islands, which are often more difficult to find.
As far as what you can do in SL, I'm pretty sure 3D modelling, texturing, and animation remain relevant. As does scripting, hosting parties, role-playing, story-telling, and sharing art and music.