I orginally thought the same way as you but I did pay for the upgrade which is if you own many of the extensions considerably lower than $500 it depends on how many you own. Datassist is DA 3 not 2 so thats an upgrade. The intergration is brilliant with saving presets of designs and forms to use in dataassist. Seriously, I am so pleased I upgraded but I did have serious doubts and was vocal about them too.
this isnt just a bundle of existing extensions it really is an upgrade to a far superior product.
Just my 2 cents..