The night's for the parents, not you.
It's a formal time/place to meet you and be reassured that their kid's in good hands.
And, despite them having access to telephone and email, practically none would drop you a line to see how things are going (and would think it strange if you did the same). That's because it's one of those professional/business relationships where people don't do the type of everyday/"maintenance"-communication you're talking about; there's only special events or emergencies. So, parent-teacher night is their only opportunity to get an objective update on their kids before the end-of-semester report.