Personally,like Markoz,I always keep all versions I have downloaded,regardless of instructions to the contrary.
I guess we determine if the new bugs are worse than the old bugs ;D
But,new buyers don't have that choice.
I guess CS have removed the old versions from their servers.
Maybe that is a shame,but it would probably be a headache for CS to have two or more versions available.Just imagine the cries of woe from newbies. :'( :'(