You don't need void rays, colossus do more than enough to take out that ground and make you victorious, especially when you have phoenix taking out vikings. But as you said you can just go Templar anyway since its by far better.
Also if you believe Thors are superior to Colossus that's a joke. More well rounded? Yeah probably, better against ground ? Not a chance. You also only listed Thor advantages... plenty of Colossus advantages. ****, the being targeted by air thing is almost a plus since at times you can force people to commit to ****ty units and simply tech switch.
The fact that you need less tier 3 units because your tier2 AIR vikings do so well against my Colossi is further proof Terran air is better than Protoss air.
As for Colossi vs Thor, I'm not gonna get into that because the original argument was "Terran air is bad" when it's not.
edit: I'm not talking about the matchup in general, I think the matchup is fine and probably most balanced matchup. I'm PURELY talking about air.