Some quotes about the 2ZZ-GE engine:
"The 2ZZ-GE is a 1.8L (1796cc) all-aluminum in-line 4 equipped with Toyota's VVTL-i technology and a refreshing peformance G head design, developed once again in collaboration with Yamaha. The 2ZZ block is bored out from the 1ZZ's 79mm to 82mm, and the bores, instead of using thin-wall iron liners, use a metal matrix composite (MMC) with bonded-in ceramic fibers. The stroke is shortened from the 1ZZ's 91.5mm to a more rev-friendly 85mm. Next, the compression is pushed up to 11.5:1, and the piston skirts are coated with iron and tin for wear resistance. The end result is only 2cc's extra displacement but a whole different world in performance."
"The VVL portion of the system is similar to Honda's VTEC system, incorporating two distinct cam profiles. However, the actual mechanism is quite different. Both cam lobes operate a single wide rocker arm that acts on both intake or both exhaust valves.A needle-bearing roller on the arm follows the low-rpm, short-duration, low-lift lobe, forcing both valves to open and close on that profile. The roller design and roller bearings on the rocker arm pivot help to minimize valvetrain friction. The high-rpm, higher-duration, longer-lift lobe rubs on a hardened steel slipper follower mounted to the rocker arm with a spring. Even though the high-rpm lobe is pushing down further than the low-rpm lobe, the spring absorbs the extra movement. At 6000rpm, the ECU sends a signal to an oil control valve at the end of the camshaft that puts oil pressure behind a lock pin in the rocker arm, sliding the pin under the spring-loaded slipper follower, locking it to the rocker arm and forcing the arm to follow the high-rpm cam profile."
As you can see, the problem is it's just really hard to get 180 HP out of a 1.8L naturally-aspirated engine. Toyota shortened the stroke, increased the compression, and even then they had to put in an extra set of cams to eke out extra performance over 6K RPM. The result is an engine whose wimpy performance at "normal" RPM ranges encourages drivers to keep their foot to the floor, which can unfortunately lead to situations such as the one described above.