Because The Pokémon Company is unlikely to sue (or even notice) such a marginal and unrelated project, I'd guess. Even if they do notice, a cease and desist letter seems more likely than an actual lawsuit; even in cases of clear substitute goods like AMR2 Nintendo prefers to send cease and desist letters first, I'm sure they don't want the bad press of suing fans. For something like Krabby, this would result in a simple name and logo change. Many people don't have ethical objections to this behavior, so the only thing stopping them would be the potential for actual legal action.
