Personally I'm glad that you decided against the exposed elements for the Robo 65 as there is no way I would have purchased it. I am grateful for the easier cleaning and reduced risk of damage that comes with the concealed elements.It's quite simple. They require more material. In our particular instance we had to make a new element design to fit our particular boilers too so we had some tooling cost here too. Larger elements that take up more surface area in the base of the boiler cost more money.
We made quite a few different design changes and tested quite a few different shapes and designs before eventually making our low watt casting for the BrewZilla 65L.
In the end the expose elements were just so much more complicated to clean the marginal benefits of this lower watt density were not realised. As a result we felt the best possible result could be achieved by making a larger casting specifically suited to the BrewZilla units that we have now.
I should also note that we have also decreased the watt density on the BrewZilla 35L too. So all BrewZilla units are sold with lower watt density than our competitors (other than BM who use exposed elements).
IMO the Guten is probably priced closer what it is worth now; if it was 60+L then it might be worth a look for $500+.
FWIW, Kegland's Q&A is about the only reason I visit this forum these days, not because I "support" KL (I prefer to use local retailers, if they stock what I'm after) but because I'm not aware of any other manufacturers/retailers who are so engaged with their customer base for product development.
I like the opportunity to find out what's in the pipeline and maybe influence things under development to be a bit better suited to my needs. What KL offers here is unique, however it seems this is also the epicentre of the childish nonsense that seems to be this forum's signature in recent times.
With the continually declining quality and diversity of content on this site, there's not a lot else here for me.