OP never said it did.
What he said was, and I quote, "we can evolve our mounts much like we currently do with pets and their levels"
"like we do with pets and their levels"
Like (preposition): similar to
we (pronoun): used by a speaker to refer to himself and one or more other people considered together
do (verb): perform
with (preposition): accompanied by
pets (noun):
http://www.wowhead.com/petspecies
and (conjunction): used to connect to words of the same part of speech, clauses, or sentances that are to be taken jointly
their (adjective): belonging to or associated with the people or things previously mentioned (in this case, the pets)
levels (noun): a position on a real or imaginary scale of amount, quantity, extent, or quality
So, using basic reading comprehension, we can surmise that he means he wants to be able to upgrade mounts like how we can upgrade our pets levels.
---------- Post added 2013-04-20 at 10:39 PM ----------
There are none, that's why the OP is saying he wants to be able to...
---------- Post added 2013-04-20 at 10:43 PM ----------
"Having an additional option that in no way affects (positively or negatively) anyone but the rider is unnecessary and stupid."
Why have different mounts at all then? Why not just have 3. 1 Wolf for Horde, 1 Horse for Alliance, 1 Dragon for both?
I'd also like to note that the OP (or myself) never said he wanted EVERY mount to be up-gradable, just ones where it makes sense.