One reason this makes us uncomfortable is that attackers have learned to originate their scans from this port, just to get through these stateless firewalls. Now, with stateful firewalling, we're in a much better situation. The firewall is smart enough to monitor the port negotiation, memorizing what port the data connection will connect to on the client. It then opens that port, and that port only, rather than the 64512 possible ports on that machine. Not only is this smarter, it's also easy to configure as it only requires one rule and no kludges.
Stateful firewalls are an incredible and obvious enhancement over stateless.
Every serious enterprise-level firewall incorporates stateful firewalling. In any case, statefulness gives your firewall memory, thus intelligence and power. Its incorporation is an incredible win for Linux. I strongly recommend that you adopt this stateful technology, whether you use it via Linux or not. In essence, an attacker sends a number of TCP SYN packets, the first packet in a TCP connection, to your host and then refuses to answer any of your replies.