Hello,
I would like to reply to this post, because this topic has been commented a good amount of time, and there are some details to recall.
Many devs are indeed aware of the interest of a trainer aircraft within BMS. This is an idea that have been already discussed and debated. Some options were imagined, but I would say that most of them were about an advanced jet trainer (KAI T-50 Golden Eagle, Northrop T-38 Talon) for example, or an intermediate training/ground support aircraft (Embraer 314/A-29, KAI KT-1 Woongbi).
Please then understand that having ideas is nice, but what we need is mainly people who achieve the work, which means 3D and coding skills mostly, but also the capability to create an accurate flight model (not the easiest chapter of the job).
As you mentioned, people are more and more demanding in term of systems and avionics. If we create such trainer, there are functions to necessarily develop that have been never done for BMS that would be very time consuming (but not impossible) to create (for example a moving map system, and backseat upfront camera screen with HUD playback).
Please also consider that since the arrival of PBR, and the lowering logic of 3D constraints, creating 3D models is much longer than before. Which means that while there are about 5 active 3D artists for whole official BMS deliverables, most of them already have their workload planned for the next two years, and are of course all free to choose the project they want.
Last but not least, if a trainer would be interesting, a backseat would be necessary to create. This would demand a huge work, for both 3D and coding. If the 3D might be done within 1 year with a good working pace (with the new specs and PBR workflow), there is no code support for it, and this would require a huge amount of work to achieve it at a stable level, with dozen of hours of beta test (to avoid avoid any MP issues for example). Also, please note that if a backseat was coded, it would probably be more convenient to make it first for F-16, which use stock avionics, and not a custom new one. Therefore, developing a custom new avionics suite with a brand-new backseat support would be a huge challenge.
With that said, I think that backseat will come sooner of later, but step by step. First on F-16, then, maybe on other aircraft.
Regards,
Radium