That's kind of my point. THe shows were basically ubiquitous. SG1 was on what? 9 years? Altantis 3 more after that? Universe 1 after that? The shows were out there 10-15 years. Even the casual moviegoer is aware of them i'd guess. That's what makes it seem less than a smart move. Maybe they can do it well i don't know. But overwrting 15 years of TV and going for a trilogy seems like a bit of a stretch
Actually, if anything, that makes a stronger case for a reboot.
The purpose of reboots, as stated, is to bring in new audiences. But the way they do that is by offering them a cool-looking film with a familiar name.
The familiarity is key here. People are FAR more willing to take a chance on something they've heard of than something they've never heard of. If they've never heard of it, you have to work a lot harder on the marketing end to convince them to go see it, or at least that seems to be the attitude of the suits.
So, with something like Stargate, it's a perfect fit, in a sense. There's plenty of brand familiarity, but not brand ubiquity. While it's true that there were many years of shows and such, even then, SG-1 was kind of a niche product. Sure there's plenty of fans here, but even here, it's nowhere NEAR as popular as something like, say, the Marvel stuff, or Star Wars, or whathaveyou.
Still, it's a familiar enough name that, coupled with a hot new cast and a strong marketing campaign, it'd stand a chance of doing a lot better than, say, a random film about people who use wormholes to travel to distant worlds and explore them.