My flying school tells me that older aircraft - c152s and Tomahawks, are in many ways sturdier and better suited to training than anything currently manufactured. Their view is that it's better to have an old aircraft with lots of placards than a new aircraft that's completely unserviceable because of something big such as a broken nosewheel.
If you're a small outfit with only a few aircraft, having £100,000 of loan sitting in the workshop waiting for a part for 6 months and not earning any money would probably close your business down.
I agree that old aircraft aren't always reassuring to look at.