Because flex uses another port for FDS instead of 80... A lot of users have firewalls installed and cant use ports other than 80 or have to adjust there firewalls. I work at a company who just can't use other ports.. When using FDS you exclude a lot of users from your application (and thus potential customers). So you just cant create like a webshop using FDS or some helpdesk at a company which restricts ports other then 80.
Another problem is you have to specify an new port for every flex application you host on your server. Every webapp needs its own fds port. So you have to forward who ranges of ports in you firewalls and systems.. I am a big fan of flex, but this would be a problem if i start selling flex to client (like big insurance agency's or large companies) because it is just not acceptable to exclude users from accessing your site.. So FDS usefull or not? (or maybe there is some way to fix this issue, that i dont know about?)
