Sometimes you get a device from a client who got it from another company who got it from etc etc. And it's been configured via internal memory to talk at some baud rate with some parity, and if you're really unlucky, it won't transmit unless it's received a command. And, like somebody else commented above, sometimes the Tx and Rx pins are just the wrong way around.

Your experiences with USB sound incredibly frustrating. But RS232 can also be crap in its own unique ways.

But to be fair, I do still rather like working on well behaved RS232/422/485 equipment, where you plug it in, set it to 9600 baud 8N1, and you just start seeing a stream of easily parsed text scrolling down your terminal :)