Well, not at all. If BW started to sell Dreadguard/EliteWarhero gear wouldn't that be P2W by "most" as you queote? Yes it would be more universally agreed upon. It would enhance/fasten the progression of a player(s)... just as much as T7 is significantly useful to doing all the new content heroics which are the new level of progression introduced on 1.6. ( if not out right required for the average player). The last statement is partly opinion, you may challenge it, but the base stat increase from T6 to T7 is sufficiently large to make me feel is accurate.
To your analogy, consider that after every horse race you compete on, you gain attributes that help your performance for the next race ( The MMO progression case), and, just as in the case of gear, the cart you carry is where that performance is built on. Thus, in a somewhat humorous way, yes the cart pulls the horse... you just bought/payed for turbo-engines
Still not buying into this part of your argument. Note that your other points I agree on so this is not a personal attack.
There's a big difference between "significantly useful" and "required".
However it's decribed (I don't care to call it P2W either), forcing players to buy gear in advance of playing released content (in the Cartel Store, by grinding, or any other method) by purposely inserting a large gear gap is a perversion on how progression is supposed to work and is wrong ihmo.
If allowed to get away with this, EA may very well introduce "Super Duper Cartel Armor" with the Makeb expansion that will be best in game when that releases. Of course, they will make it possible (but prohibitingly painful) to grind for the same way these T7 parts are.