I kind of feel the opposite about the whole monstrous creature thing. When the riptide was announced as a monstrous creature it never sat right with me. Even the Wraith Knight makes little sense to me, its got a pilot and its a machine, its not a creature of any sort no matter how many spirit stones you cram into it. I would have much rather had all the "monstrous machines" left as walkers with individual special rules to characterize them appropriately.
All that being said the only thing that needs to happen for dreads is more survivability. 5++ would probably do it, with the option to purchase better invulns. Venerables should get another hull point for a total of 4.
CSM dreads need a 5++ baseline and the options to take "marklike things." Nurgle should give them shrouded, Tzeentch should give 4++, khorne should give rampage and Slaanesh should give IWND to make up for vehicles not getting fnp.
also, non khorne marked csm dreads should have the option of taking psycher levels because that would be awesome.
I think ork dreads are fine as is, possibly with the exception of giving them the standalone option to take a KFF without needing a Morkanaut or big mek chaperon. Possible points reduction might be in order too.
also making the unit size 1-3 for all of the aforementioned 'naughts would help immensely as well. It's impossible to run my (admittedly hilariously useless) dread mob composed of 2 deff dreads, 6 killa kanz and a morkanaut within a single FOC, which makes me quite sad.