The Standard Model of Cosmology is not complete
And we know it. That's why every time something that might make a crack in it, people get excited. However, because the Standard Model has been so very, very good at describing and predicting what we see, all these potential issues come under a lot of scrutiny. As they say: "extraordinary claims
require extraordinary
evidence". The Electric Universe theory is pretty much like the flat earth model: it doesn't work. It doesn't confirm with observations. It doesn't predict things.
The reason we have these 'mysterious things' is because we observe them: the light particle/wave duality is something you can witness in high-school experiments. Gravity waves have been observed. I deal with building radiation detection sensors and work with strange quantum effects to make them work (same as modern micro processors have to). Time passes differently on satellites because of their speed, and relativity is needed to make something like GPS work. Dark energy/matter is just a placeholder because observations show there is something causing the accelerating expansion of space-time.
The important thing here is that all these aspects are not some random stuff 'arrogant scientists' come up with. The observations match the model. With things like the Electric Universe theory, the observations do not match the model or the predictions it makes at all, and is therefor rightfully discarded. That's how science works. It's slow, it's tedious, with lots of arguments etc. but it works an it's the best method we have.
So as far as I'm concerned there is room for ALL theories
Scientific theories have a very well defined definition, which is why Flat Earth isn't one for instance. The Electric Universe hypothesis has been shown to be false, and is hence not a theory.