Not really. 8-)
First of all i'm not sure which question you were trying to answer,
even (today's, i.e. "veto, anyone?" or a previous question).
Is your intent here to say that really, "the mips sim will/must be
done the way you outline above," or is it to provide a rationale for
why you think it should be done that way. (to my mind, it could be
either; you're a mips sim maintainer long before i got here.)
This is the way it has (ment to) been done for all MIPS ISA variants
since igen replaced gencode. You've proposed a change to that process
so I'm [trying to] explain the rationale behind the current status-quo :-)