"Elected representatives would make better decisions if they didn't have to worry about what voters wanted"
While no-one is so bold as to put it that way, that's the core idea underlying the push for a longer parliamentary term. But when put like that, its flaws immediately become apparent. Better for whom? Certainly not for voters! Otherwise, they wouldn't need to worry about what we wanted.
But apart from tacitly endorsing dictatorship, it also misses the point. Democracy isn't about making good decisions - its about making our decisions. And so politicians should constantly be looking over their shoulders and asking themselves "is this what my voters want"? "Will I lose my job if I do this"? And if they're not, we need to ask: who are they making those decisions for? Because it certainly won't be us.