Yes, but Warlocks in particular were neigh incapable of doing anything useful in heroic tier without decent implements, which PHB1 didn't manage to provide in general. Other classes may lose just as much, but they were already able to fill their roles for the most part. There are however a number of 'glue' type items in both AVs that are quite desirable to have in the game, like songbows for instance.
I just checked Compendium, Songbows are apparently Bard items from AV2. I don't use AV2 IMCs, yet somehow the Bard PCs are able to function.

Is this all just some min-max powergamery thing? Or are certain classes genuinely dependent on particular magic items? If so, please explain how. Maybe use the Songbows as an example.