TSPP is one of the best coded games ever. It's all because of the great stackability.
There are so many ways to approach the game that you don't really need to suffer through a long game to be challenged and crank up the score. Stack the modes and finish them in a single ball (without draining or timing out the clock) and you'll blow up the score. Combine it with double scoring on shots and it's through the roof. This approach can only occur on a single ball. If you started several unfinished modes and drain, kiss this potentially high scoring approach goodbye.
But if you prefer depth that can also be had with several balls, TSPP still delivers beyond the TV modes. You will see modes that open up only when more accomplishments are achieved (Treehouse (crazy extra ball, Apu's Giveaway, Nuclear Disaster, Krusty spinner etc), Pretzel, Secret Stash, Alien Invasion). Heck, if you can wind the clock up to a full 60 seconds, it'll light an extra ball. So much code. It's the best of both worlds.
JP is good too, but TSPP set the standard for a non-repetitive deep home game. Sounds like the routed Simpson's you play is not a good example.