That is indeed a significant and important-to-catch change in the document checklist and likewise in the Guide for making a grant citizenship application. Good on you; the forum should appreciate this.
Date of change as noted in the instruction guide was June 16 but as is typical these days, such changes often do not show up in the forms or instructions until days or weeks later. But it is there now. Including as you note, the requirement (even if poorly structured as it is stated in the checklist) to submit "
colour photocopy of all pages" in the passport.
It is moreover an interesting change. Can think of numerous possibilities for why they have made this change, but all that would be speculation at this juncture.
It would be interesting if someone took the time and made the effort to submit an ATI request (not to be confused with the ATIP requests more often discussed in this forum, which are for personal records) for copies of internal IRCC memos, letters, statements, decisions, and so on, regarding this.
There are many discussions in this forum about vagaries in enforcement of the requirement to provide a properly authenticated translation of stamps in passports. For example, I recently went into some depth contrasting the scope of the instruction/requirement (basically it is universal, anything not in an official language needs to be accompanied by a properly authenticated translation for any document submitted or presented to IRCC attendant just about any and every application, including citizenship) with the common anecdotal report that it was "fine" or "OK" to not include one; that was here:
https://www.canadavisa.com/canada-immigration-discussion-board/threads/request-letter-passport-copies.738496/#post-9557348
The instructions are clear: include a properly authenticated translation.
This is even more clear now that the instructions specifically state the applicant is to submit colour photocopies of ALL pages in the passport with the application itself, which is thus clearly covered by the overriding instruction near the end of the guide in regards to providing translations.
One might surmise the lax enforcement of this will continue, and as you say if the information is otherwise there and easily understood, the failure to include a translation might not trigger non-routine processing, not even a request for the translation. In the past, in many instances it was readily apparent that if it did not matter (that is, the processing agent was confident about the information as is), it would not matter the translation was not included (been there, benefitted from that).
BUT the fact this is now part of what is to be included in the application POTENTIALLY changes the context significantly. If the check-for-completeness screening, done when applications are first opened, includes screening to be (1) be sure passport copies are of all pages, and (2) that any information not in an official language is accompanied by a translation, failure to include a translation could result in the automatic return of the application as incomplete. We will have to wait to see anecdotal reporting to see how this goes . . . or here too, someone could take the time and make the effort to submit an ATI request (again, not to be confused with the ATIP requests more often discussed in this forum, which are for personal records) for copies of internal IRCC memos, letters, statements, decisions, and so on, regarding the completeness screening, that would be interesting and probably helpful information.
A GUESS: Generally I would avoid guessing about how things work, or will work, but given the odd structure of the statement instructing applicants to include all pages of the passport, but then explicitly stating to include the biographical pages, my GUESS is that for at least awhile IRCC will not be screening incoming applications and returning those not including more than the biographical pages, let alone not including translations. I do NOT offer this guess to suggest anyone test it or otherwise fail to follow the instructions. I mention it because I think we might see anecdotal reports saying it was OK or fine even though they failed to follow this instruction. It could be a mistake to rely on any such anecdotal reporting.