With all due respect to you and your source, history has proven not be believe anything anybody is going to do until they've done it. Even then it is wise to double check to be sure...
Well, it's not just that.. Other 'users' were not 'fan' of updating their OS.. So if MS ain't releasing an Updated ISO, many will surely 'missed'.. It's also a pain in the *ss to install 8.1 then Update 1 if you're formatting frequently or installing on many PC..
So you're actually saying that installing the 8.1 ISO + update 1 MSUs actually takes twice as long compared to just installing a single iso! Updated ISOs would be a huge timesaver!
Not to mention the Background Int service doesn't work on the first boot of 8.1 so you have to reboot to even update windows.
It will interesting how will be the installation options and display of Update 1 ISO - if it will be like win8.1 ISO.
Why are you waiting for the MSDN subscribers release, if we have already the RTM version of about a month if i'm not mistaken?
MSDN will probably get full ISOS, so far we only have MSUs, the MSDN release would also 100% confirm that 17031 is RTM (we already know that 99.9% sure, but MSDN would make it official)
Is there a way to turn off creation online accounts that new user has possibility create only local account?
There is a way perhaps of creating a new account and then say do for later. The 100% easiest way is to turn off net (hardware LAN/router turnoff) during install. That way, you will not get even a prompt. Turn net on after install on start screen.