Hmm well it would be a great thing if Yahoo! decided to fix some bugs in their client aswell.. I have two issues with mine:

-under WinXP it takes over the CPU and inhibits all other processes
-under RedHat I cannot read the characters.. they all have these boxes around them...

As for the issue concerned... I guess it's Yahoo!'s right to do so anyway, but as said they lost a lot of users...