Rime royal vs. blank verse

On HLAS (the Shakespeare Authorship) newsgroup, I asserted that is easier to write blank verse than "rime royal" but was challenged by Tom Reedy to write some blank verse, which I did,

My Lord of Reedy asks that i write verse
that's blank, containing no end-rimes:
quite difficult for me, since rimes spring up
in mind (like leaves upon the maple bough
outside my house this fecund time of year)
but which i must reject, or play the fool,
as if I wasn't taught to write in class,
or Frosty school of poetry, no less.
No near-rime like the one above will count,
Nor echoes in these five-beat iamb lines:
(Like end-time prophets calling on the past
To motivate the listening audience)
Full twenty lines, Tom Reedy asked me for,
So that he might not toil on "rime royal"
(As Shakespeare did in his long narrative
About Lucrece). I challenged him to prove
How difficult it is to write -- much more
Than unrimed lines of five-beat iamb meter:
Da-DAH, da-DAH, five times. Not four.
The line above falls short, and this one's one-beat long.
Just five is all that's needed or required.
And that should do it, don't you think? I'll stop.
Now is Tom Reedy ready to write back?
Two stanzas ought do, since it's so easy:
A-B-A-B, another B, two C's
C'mon then, Tom, place fingers on the keys
And rime us royally, if it's a breeze.

which proves nothing, but leaves the questions unanswered as to why the author William Shakespeare chose to write a lengthy narrative poem in this very demanding form (rime royal) about a very demanding classical topic (the expulsion of Roman tyrants and the installation of a Republican form of government, which was more democratic) and dedicate it to a very demanding young nobleman (Henry Wriothesley, 3rd Earl of Southampton). I'll put in some links later. Too much going on in the world outside today.