[precis] rationale of rfc7613 decisions

[Nikos Mavrogiannopoulos <[e-mail]>]

Hi,
 I'd like to update an rfc in order to follow the rfc7613
recommendations for passwords, however I'd like first to understand the
reason of the restrictions applied to passwords (i.e., freeformclass
choice, space elimination, etc.).

I'm checking both rfc7564 and rfc7613, and I cannot find the rationale
of the restrictions being done. In particular:
 1. why rfc7613 restricts all spaces for passwords to U+0020?
 2. what is the purpose of "Contextual Rule Required" in section 4.3.2
of rfc7564?
 3. why freeform class doesn't allow "Old Hangul Jamo characters"?
 4. why freeform class doesn't allow ignorable charaters?

The context of that, is that I am trying to understand what would be
the drawbacks from recommending a fixed normalization form (e.g., NFC),
for passwords, in contrast to recommending rfc7613.

regards,
Nikos