Making solar and storage cheaper is already engineering.
I do expect fusion to out-compete solar and storage eventually, but probably not in the next 50 years unless one of the fringe groups does something amazing.
What is being done now could be viewed as engineering, as the goal is to scale the process to a large size, such that the system may deliver a 10x return on the power going into it.
edit - and ITER has not been inspiring confidence. They seem to be massively bogged down at the moment, though we shall see if anything picks up now that they have swapped management and are trying to rebuild the organization.
You can try to engineer cost savings and efficiency out of the current solutions, but using all that brain power on something that might yield single digit percent gains is a massive waste of talent IMO.
The minds that are working on those problems would be much better utilized working on solar and storage research as well as more long term solutions like nuclear fusion (NIF, ITEF).
Without the government subsidies, the market for current gen PVs and batteries would be infinitesimally small.
Wouldn't it be better to spend those subsidies on research for better PVs and batteries?
edit - energy production is always subsidised in wealthy countries, as energy security is key to national security, so it would be stupid not to.
You could, but I don't think it makes a lot of sense as an argument.