I suspect that Elias was referring to past efforts where the spawning was so good that the tendency was to respawn the dead from many swarms back onto a single "super-swarm".
Personally, I like the V9.0 list a lot as it is a big improvement on past lists and does give the intended "feel". However, I am also a bit unsure about the "big" bugs, both uncommon and independent. To take up Elias' point and your reply a second, by definition "expendable" critters should be capable of respawing, and obviously the bigger they are, the rarer this event should be. But I think the list falls between two principles. "respawnable" critters ought to be capable of doing that - but the reduced points mechanisms together with the high respawning costs make that all but impossible for any beast over 4-5 points value. However, if you start from the presumption that you are not in fact going to attempt to respawn them at all, then they do seem quite cheap and powerfull. Independantly, Olly and I both came up with a "big critter" list, intended to field as many large beasts as possible.
See here for Olly's list Mine was similar :- three Hieraphants (275) and a set of Lictors (150) with two Vituperaptors, two Assault groups and a Hive tyrant, together with two Hierodules and a Trygon - Eight on-table activations with a third/fourth turn objective grabber, comprising 5x 6DC critters, 2x 4DC and a 2DC brood.
See Hena's battle report here.  In both cases they do seem to cause most opponents great difficulties while being easy / boring to play.
So, for "uncommon" WE, perhaps they could do with a slight upwards points tweak, (to make them rarer), and a downwards respawning point nudge (to give a slightly better chance to spawn). Regarding the independants, I am really unsure about having three DC6 beasts available, even if they are 'easier' to kill, so again, I suspect that an upwards points tweak may be in order. In both cases, and also for the Vituperaptor and Dominatrix, I also suspect that the DC values could be reduced by 1 point. In my game, I had 7x DC4 and DC6 beasts on the table, soaking up MW and crossfire shots from Hena (who was playing his marines very skillfully) and at the end, I had lost a single Hieraphant, all but 1 DC on a second, and a Hierodule (because Hena managed to kill the Hive Tyrant Synapse). Admitedly I was unusually lucky in some of my dice, but even so, Hena's Marines were mostly reduced to bloody smears around these big beasts.
Regarding the debate on Lictors / Gene Stealers; part of the issue lies in the restriction on which Nids can claim / contest objectives, which has an intentional impact on the way they are used. The point is that, going into turn #3 you obviously need to have around six appropriately placed formations to stand a chance of contesting the six objectives. If you have less, then one or more objectives may not be contested, reducing the potential for winning the battle. While you can use them in the ways you describe as a 'tripwire' or distraction, throwing them away in that manner will also reduce the 'Nid's capacity to control objectives.