Not guilty was inevitable given the threats against Republicans who would otherwise have voted agaist Trump (apparently).
From the little I know of what happened over there, I'd say that in English law there probably wasn't quite enough to convict as the language wasn't sufficiently blatantly calling for direct insurrection. Obviously they have their own burden of proof; I'm just saying what I think the result would have been under our law.
As to whether it was a waste of time, that is a different matter. There are occasions that a case goes to trial in the public interest rather than purely on the likelihood of conviction.
Hence I agree the trial should have gone ahead in spite of almost inevitable acquittal.
Regardless of his policies, good or bad, what shocking behaviour by Trump though. On the day in question, 'throwing Pence under a bus' in spite on Pence showing incredible loyalty to him throughout his term in office. That alone says all one needs to know about the man.
The GOP have been taken over by 'Tea Party' type nutters.