You spoke as though a similar motivation makes two actions the same. It doesn't.
It does if actions you've specified that qualify someone to 'playing god' are very vague and oft interchangeable.
And yes, that is precisely what you're doing. One can't possibly put all these different actions in the same category as Solas. Of course, our heroes can dabble in politics and choose a new ruler, but Orlais still is Orlais. Ferelden remains mostly the same.
... Yes, because the point of Inquisition was just "dabble in politics", instead of saving entire South from wannabe god, that was about to invade them all with a demon-army (plus sealing of the Breach, which - as we've seen in future Redcliffe - would eventually tear the world apart). Totally...
Neither countries remain the same after that, because whatever you may want to think about other decisions we've made, the decisions Inquisitor has made, including "minor" ones - picking de-facto emperor of the South, picking head of the Chantry, picking allies in helping to seal the Breach, ending civil conflicts in both countries, negotiating peace treaties between Tevinter and Nevarra and so on, rewriting the history of Thedas by making shocking discoveries - impact the entire Thedas on macro scale.
...Not to a point tearing the Veil would, not arguing that, but considering that we don't know what decisions we'd have to make now, that we have to oppose Solas - which may include changing the world ourselves in some significant measure.
The Inquisitor may save the world, but his/her idea of saving is just keeping people safe.
Keeping THEIR people safe, so far as we don't know much about Solas' actual people.
Solas' approach usually doesn't merely involve affecting the way people live or think as us mortals do when we take up a cause. He'd rather modify the literal planet moving around the sun directly. Like a god does.
Making decisions that affect the planet doesn't yet make people gods - sometimes is just an effect of necessity, or after-effect of living after achieving certain level of technological aptitude. We, humans, actually affect earth on macro-scale now - global warming, large geological changes, etc.... can we even begin to try and call ourselves gods?
No - just because the scale of our effect on planet has changed, and we 'technically' have "god-like" powers, especially compared to our ancestors and their limited scale of impacting their society and environment, doesn't yet make us gods.
It's actually the whole point of portraying Elvenhan and Evanuris the way they currently do - theirs was the civilization that has achieved such level of magical and technological aptitude, that compared to modern Thedosians they could be considered gods. They weren't though - their decisions have shaped the planet, true, but that has not yet made them gods and, if we believe Solas, their claim to divinity was false and so was their demand from others to treat them as such and serve them. That is what Solas was against - not about making world-changing decisions, which (given favorable or unfavorable circumstances) could be accomplished by anyone.
This is exactly why he says "I have people, Seeker. The greatest triumphs and tragedies this world has known can all be traced to people."
It isn't about being gods or "playing god" - sometimes things have to be done, and they aren't done on a whim. Solas gambled with fate of the world ever since he's decided to go against Evanuris - he saved it once, and pretty unarguably is the creator of modern Thedas, but his victory came at a terrible cost, which he thinks caused great injustice to people on both sides. So he's trying to reverse that. I don't think anyone here, or even Solas himself, is happy with the method he's trying to do that - but this is also why we, ourselves, will likely be "playing gods" in DA4.