The nice thing about the Raider, I think, is that it can adjust its job very easily. Build a Raider-II with the Instigator title and Overload Impulse, and that's about all you need. If your opponent brings fighters, the Raider can tie them up and hit them while your Imps go to work. Alternatively, if your opponent brings no squadrons, you can have the Raider tag-team with one of your Imps, increasing their effectiveness.
It's sorta like playing rock-paper-scissors, and having both rock and scissors at the same time.
I agree. Out-of-the-box, it's immediately good at two things: shooting squadrons (2 black dice/1 black, 1 blue), and quick flanks (speed 4 + black/blue dice). For 44 points, this is fabulous value. At 39/44 points, a CR-90 is good for flanking... and never gets good at anti-squadron. A 51 point Neb-B is good at sniping, and a 56 point Glad is good at flanking and brawling (for a short period of time), but neither gets respectable anti-squadron fire until 57 and 62 (13 and 18 points more than a Raider, respectively).
The Raider can also be easily customized to fit either role (anti-squadron or flanker) easily, and with an ion slot can also take on a third: mid-ranged disabler. For 8 points (Overload Pulse), a Raider can soften up a meatier target. For 9 points, it can take an anti-Squadron title + Quad Lasers to increase its potent anti-squadron capabilities. And for 11-12, it can increase its offensive firepower against enemy ships (Ordnance Experts + ACMs/Rapid Reload). None of these refits on a Raider I are more expensive than a naked Gladiator I.