Uhm, so they're rebuilding/restructuring the core classes? Because it doesn't look to me like a simplified version of cleric, e.g. regarding domain powers and automatic domain feats.
In the light of all the revisions and errata they've released this year (including the "updated" monster damage and the new direction with racial stat bonuses) it seems to me like a revised edition (4.5 or whatever you want to call it) than anything else. If the Essential books are supposed to be a different, simplified version of 4E (similar to Basic D&D), I wouldn't market them as 4E supplements; why mix different versions of the same powers -- or even different versions of the same classes? I wouldn't allow, say, an Essentials cleric in the same party with a core cleric.
I think it would be far, far better just to say "Look, guys, we have revised the game so much that it's time for 4.5". I don't know about you, but to me it seems like they're trying desperately keep from going back on their promise ("There won't be a 4.5") even if the game would actually benefit from a new set of revised and updated core rulebooks. I would definitely buy them, because one of the reasons I haven't bought any 4E books is that they're not including revisions or errata in new printings (and I'd hate to print out 100+ pages and start doing it manually).