It cost them $74 million. I'm going to predict it now - in about 10-20 years, wealthy hobbyists will be sending probes to other planets, eventually creating a worldwide community of amateur planet probers.
For example, the Russian Fobos-Grunt[1] mars mission got stranded in LEO. Though indeed not in a stable orbit; it did re-enter and burn up two months later.
In fact, if launch were significantly cheaper then Earth orbiting satellites could be equipped with special sub-systems designed to deorbit them if the main satellite became inoperable.
Actually, that's rather like an anchor.
Either way, there are practical applications for Kessler syndrome, although in the context discussed here, of course you're right - last thing anyone wants is junk all over the shop while trying to carry out space travel.