There are a lot of long comments here, which I haven't read, so this could have been covered already! Excuse my ignorance, but let me just talk about it from an 'inside' perspective.
Plastics for a consumer are about several things.
1) Reliability - All plastics are seen to be fairly similar, therefore many think there are no miscasts in plastic.
2) Multipart - Plastics are limited, so must be in multiple parts.
3) Multipose - a lot of people get this mixed up with Multipart. Multipose is nice, but, unless made by really skilled people, it can result in odd looking poses. I am still a little cynical about Malifaux multipose, for example - yet their multiparts are stunning, if assembled well.
4) Cost - Consumers often connect plastics to a low cost. It's not always the case though.
Plastics for manufacturer have different points.
1) Volume - If we know we are selling several thousand of this single kit, it's worth putting the effort into plastic. If you are selling thousands, you can keep the end consumer cost low, which increases sales of volume. However, for smaller kits such as character models, you often have to charge proportionally more. A good example is our Aliens sprue (Approx 3-15 per customer), it will sell more than the Predator Sprue (Approx 1 per customer), therefore, it will cost less than the Predator sprue.
2) Product Identity - All the 'big' companies use plastic. Therefore, to be considered 'big' an easy way is to use plastics. It's a big investment though!
3) Speed - Once the tools are made, printing plastic sprues does not require a lot of time.
So there are a LOT of reasons a manufacturer will choose to make plastics and, quite often, one of these points will be ignored. For Malifaux, it is 'multipose'. They know what they do well and that is making nice figures. I would assume it is the same for your plastics from Dreamforge/Dreamblade/Whatever (I forget their name!).
It's gonna be the same for us, for the Predators to look great, they cannot be multipart. The Aliens, however, are a bit easier to do this with. Again, the Colonial Marines, to look great and not like generic Imperial Guard, have to be multipart, but not multipose.