This is the case in Reach as well. A pixel-thin tracer that you'll see for about half a second before you explode (any good laser-er won't charge with the reticule actually on the vehicle specifically so you can't see it coming) is really terrible warning.
People have made the case a lot in here for the Grenade Launcher as the best addition to the sandbox in the series, but for my money, the Plasma Launcher is the most important addition--a small but significant distinction. It's easily the best (but not most effective) antivehicle weapon in the series, period. Doesn't have an incredibly fast travel time and pinpoint locking like H2 rockets, isn't a highly effective sniper rifle capable of crossmapping both infantry and vehicles like the laser, requires at least some effort by the attacker to get a multi-kill. Both the weapon charging and the projectiles have a loud, distinct sound associated with them to aid the driver of a vehicle, and the shot is slow enough that cover can be found, but only if the driver is good at his job. Halo is cat and mouse gameplay at its core, and this is the first time they've managed to scratch that itch in the vehicle sandbox.
Then they brought the Laser back instead.