I say this as someone who helped in small ways to develop open source alternatives to Matlab.
BTW I don't begrudge that TileDB has MATLAB support.
I see plenty of modern scientific/engineering workload in my day job. From what I see around myself it is usually a handful of people set in their ways that are holding others back by keeping a ridiculously overpriced tool alive that has comparable if not better alternatives. I gather from comments that it is different in Europe.
You are right that engineers are conservative which no doubt plays some role. But I'd say technical debt and legacy code plays much more of a role.
Most Engineers (Chem, Mech, Matls etc) are not exposed to code during university. Maybe it is changing now but it is slow process. Often first exposure comes when the engineer enters industry and is asked to work on existing model - usually under supervision of a senior engineer. You learn whatever the language the senior engineer knows and that is typically what they learnt from similar mentorship - it is often Fortran or C/C++. Our Industrial Process has not changed dramatically in last 30 years. So once efficiently written and accurate simulation code exists very little reason to rewrite (if given the choice to rewrite an existing model in whatever the current language du jour is or continue to hack on something that already exists most engineers - at least the ones I know, would chose to hack on existing code). For pretty much this reason there is a heap of Fortan that is still alive in my org (with roots that can be traced back to the '80's). I think it's probably worth mentioning a lot of engineers don't approach code thinking about algorithms - it's equations i.e. I need to write something to solve Bernoulli's equation - or Ergun's equation or similar. Linear programming (i.e solving simultaneous equations) is the other main reason to write code and hey MATLAB does this pretty well...
The other reason for being "gunshy" about new technology at least in my org is that a lot of the senior engineering people still remember when we got bitten by investing in Microsoft "Stack" in the late 90's. There were a lot of Modelling done with VB6 and Access which tuned out to be a technology dead end. Access databases in particular have plagued our org in many cases multiyear effort to migrate something out of Access. Open source probably protects against this but everyone wants to be sure any new technology will still be around in 15 years time. I think that is why people in my org are finally starting to look at R it has passed that initial hurdle and there is some confidence it is not just a fad...