Nothing gets tossed in any imaginary bin. That's ludicrous! Whether or not external is better or worse depends on several factors such as overall amount of expansion, the price performance of that expansion, the compatibility or support for future (potentially faster) devices, and so on.... Not whether or not Apple decided to wire the eSATA ports.
Silly nonsensical argument.
Sorry, I disagree. When there's a capability feature that exists, it has been "paid for" even if it is not being used.
Granted, it is often cheaper to use an off-the-shelf design that has extra widgets instead of a perfectly tailored custom design, and in this regards some of these extras can be thought of as "free", but this is really an "Apples vs Oranges" cost comparison: the off-the-shelf chip is cheaper not because it contains more, but because it has higher production volume to lower costs. Essentially, the extras on the OTS chip resulted in a 'tax' which was paid by all of its customers, and the magnitude of this 'tax' is less than the cost of a low production volume customized run.
Or in other words, the OTS chip provides a more favorable cost:benefit ratio because the cost went down, not because the benefit went up.
Getting back to this specific case, all that is really being said is that the cost:benefit of the nMP may notionally have be able to have been made even better had this particular "benefit" been employed, since most (presumably) of its costs were already paid. Of course, this is still just notional and has its own technical assumptions. Specifically, it is being assumed that the cost to wire up those "paid for" SATA ports is reasonably low.
If the "wiring up" cost were to be excessive, then they become not worth bothering with, and what this is driving at is that TB very well might be the cheaper alternative...but even here...
...we all know that eSATA is another technological option to provide a capability, so adding wiring from the board to external port(s) doesn't really sound like all that significant of a cost to be a barrier. What's IMO more likely is that Apple made policy decision that they don't ever want to sell a Mac which comes standard with an eSATA port, even thought that has a benefit potential for some of their customer base.
-hh