Remove the "guess" part. Some extensions are available to everyone, like Sandbox and Dynamic Components. SU can even be an engine for computer games. Odd that there was a complaint here about the lack of "primitives" as that was one of the first plugins the SU developers released. That extension is now open source, for anyone to add stuff, and the primitives are parametric - meaning there's an option, through the context menu when the primitive is selected, to edit the form.
And a very notable "other developer" is Trimble SU itself. They are developing several extensions geared for Pros - from recently acquiring Safaira and the Trimbnle Scan Explorer that SU-uppifies the interpretation of point cloud scans. And now components can now be set up as classified objects - yet another new thing for the Pro-crowd.
Another big benefit of having extensions to customize a program is that they can be updated more frequently, and independently of the base program, and often are backwards compatible. Which benefits people who cannot update to the latest release of SU. At least the extensions can be updated.
Let's not forget about the my.shetchup beta going on now which brings SU modeling to anyone with a modern browser and will interface with Trimble Connect.
@ChrisStewart, @Sonder already wrote that he spends 30% less time creating his CDs in SU/LayOut than he spend with ACAD. And if you want to see another example of some sexy CDs, look at the Basecamp 2016 video from a structural engineer that Nick lassoed and brought into the SU fold. Years ago I listened to another basecamp presentation from an engineer explain how SU modeling got more interactive input from other project collaborators resulting in better communication and less costly mistakes - decreasing the likelihood of costly lawsuits later on.
I don't get the complaint about mirroring components being a work-around. SU developers opted for the K.I.S.S. approach, and like many around here, not being encumbered by a mirade of program tools feels natural to me - like working with clay.
Kitty half components extruded from exploded 1/2 circle, later making one half unique to finish sculpting the asymmetrical bottle. I don't see much of a seam, but even if I wanted to merge the components, I still keep the original half components around in case I want to tweak something.
More mirrored components:
The one with the hands had to be merged, but its original component half is still around if I want to do something else.
From my view, horrid workarounds meant doing things like using the program Vitrite to make a transparent overlay over the SU workspace to try lining up a SU model to an existing image. But now, with SU Watermarks and using Advanced Camera Tools to set up camera positions using the data from digital photos - another extension for Pro-users - people can create SU animations matching digital imagery that are more than good enough for a court of law.
Another thing people seem to forget is copyright and patent law. Programs are copywritten property and things like Push/Pull is patented. Somewhere in the mix this comes into play when wanting to duplicate tools from other programs.
I still have the SU4 installer. Its last Windows maintenance release was a whooping 15.7 MB file. 40 MB SKPs were considered huge. It come a long way baby.
And now with SU17 requiring users to have hardware acceleration graphics capability - that's a big change to the system - and laying the groundwork for more things to come. This has hurt some people whose hardware cannot support this requirement, but computers have made steady progress. Notably Intel graphics. Kudo to Intel for their OpenGL modeling support. Several years ago my local Intel plant advertised for an OpenGL driver developer to develop drivers for professional level OpenGL modeling. It took a few years, but it seems SU17 users with integrated graphics are reaping the benefits of Intel investment in their drivers. That's just one example of the time and investment companies make to upgrade tools, features, hardware, drivers. It's not trivial.