It's a common marketing practice

This is so common there's even a term for this: "mid-life kicker".  This applies both to doing
a product upgrade in middle of a product's lifespan (which is hardly controversial), and also,
I think, to the idea of "slugging" a product at launch and remove the "slug" for a fee when
doing the upgrade.

While this looks rather insane to some people, it is quite a sensible business practice - the
company can sell the initial product for a somewhat lower price maybe, and grow the market,
then release the faster/better product via upgrade without actually shipping new hardware to
existing customers.  Overall costs are lowered, and in a competitive market both the new and
old product should cost less than shipping an entirely "new" product.

Of course it does depend on customers not finding, or being unwilling to mess with, the
"slug"...