we almost agree, but not.
functionless proteins? yes , I guess it could be (but protein killers like ubiquitin will trash most of them)- but, be carful not to mix "functionless" with "useless".
and I will explain:
even a "usless protein", one that has no catalitic function, has an effect, how so?
it may bond to other cellular components, or aggragate in the cell (usually it is bad news for the cell), or change the osmotic tension by its sear existance.
you see, no free meals and easy answers in biology.
there are no inert proteins.
they all count.

about the other part, i must compleatly disagree.
unless we are talking about a strees enviroment, exposure to hunger (and so on), I believe the body (or selection, if you want) will NOT minimize the energy loss of these "functionless proteins"
we are very enrgy wasting.
that is the fundemental differance between a human made machine and a nature made machine- nature, unlike us, does leave loose-ends in it's creations