It just bugs the hell out of me remembering that we could at one time, but now we can’t. Making all objects available in all themes would still be a step forward.
Right?! Why isn’t it like that now?
Back in TGC1 days they (HB) said it was because of file sizes and memory issues etc. but a lot of that kind of stuff have already improved massively.
For example, when Scarpacci and I originally built the Valle de los Reyes (Ballesteros) course in TGC1 it was a huge file size back then, mainly because there are actually three full courses built on the same plot but also because believe it or not the entire plot was totally covered with individually hand placed brushes of heavy rough around every single auto-generated tree

The plant meter was completely full and to get it to even publish we had to delete massive amounts of stuff from the edges of the plot and around the second and third courses.
When that same plot got ported over to TGC2 the plant meter wasn't even half full, and then when it got ported to TGC2019 it was even less.
Lots of us have suggested time and time again to get rid of the theme restrictions in the designer and have it on a limited number of "slots" available for each category system - so things like:
Theme - slots = 1
Background - slots = 1
Trees - slots = 6
Bushes - slots = 5
and so on.....
It would then be up to the designer to mix and match what they wanted from ALL the objects available in every current theme, whilst at the same time allowing HB to keep things like file size under control by only having the limited number of slots - this number could then be expanded in the future as/when their tech or code would allow.