I think that to some extent they see "half" figures as "lesser value" than a full size one, at least in terms of "Sellable" to consumers. When people see a standard figure for $15-17 hen look over and see Ewok, Yoda, Jawa etc. you can't help but feel the "value" isn't quite there. And you only have to look at how they handle DLX line to know Hasbro's take on "perceived value".
One main issue is that the kids in question aren't as easy as reusing Ewoks or Jawas for the various characters or repaints. SC for instance do not appear to share any parts aside from maybe legs for two for them. Same with Leia of OWK, S1 Ezra and a few others. Now we as fans can see some reuse in certain characters, like Omega and a Clone youth. But, is there a call for a Clone youth in the line or would it peg warm like that last one in 03 did? There's also the lack or awareness with TV on steaming that makes a lot of those tertiary character a higher risk than they would be if on national TV, or even syndicated on Cable. One would think that making several characters from BB would be a given in the 05-09 era, but today it simply isn't viable
Had BB aired on Disney Affiliate Channel like both TCW and Rebels did I think there may have been more of a demand for a quasi-dedicated line, though likely 5POA. But with the ratings for TCW, and lesser extent Rebels there was visible data to go on who where the market might be. With D+ they have no idea because shows typically only get one season, and they don't know the ratings of said shows until months after it needed and eve that id a nit nebulous. With standard TV Neilson rating they knew a show had 2.3-3.2 million viewers week to week per episode, but with streaming they go by minutes watched which isn't exactly clear how its broken down.
By only having it on D+ you're essentially cutting yourself off from millions of potential viewers that might watch it on regular TV, either at grandparents house or Auntie and Uncle's. For the people beyond/outside of the collecting circle awareness helps sell toys, and at present there's not a lot of awareness on Star Wars especially is they cannot find it in stores. And even then, the coverage of 3.75" consumers is likely a very small drop in the bucket compared to the other kid lines.
It has felt like to me that 90% of the line should be an online only presence geared towards collectors as a DTC type experience, because aside from the main characters it all seems a big risk with the amount they have to make in order to be profitable. I don't think every character should come about via inclusion of a HasLab vehicle, but they should look at doing collector club multipacks for them because not everyone wants to have to buy the ship to get the figures. As much as I liked the design of Onyx Cinder 2.0 I don't want to be locked into getting it just to get the kids. Mainly because I don't buy every figure to be said character, 30% of my purchases are strictly custom fodder purchases. Which is what SC would be, as was Acolyte.