The original is fine. Your suggestion is slightly off and would require a few small changes.

You could say it either way (although if you go for the second, it's probably better to keep the tenses consistent). The first way is basically an inversion of the usual order "The effect ... has been more important".... The second way is more of a relative construction meaning much the same as "The thing which is more important ..." and keeps the usual word order.

There is nothing wrong with the grammar. It is complex, though. "More important for technical communicators" is a noun clause.

I would say... More relevant to techical communicators is the impact the tech revolution has had on the working practices over the past decade.