To your first point. Yes he is a drop off from Border, almost half of his hundreds came in one series. Over 15 tests he averaged 24 in England. But as you said wouldn't stress on that right now.
McGrath made his mark over the 2nd half of his career on such pitches, Cummins and Lindwall has some experience and success on roads as well, it happens, those are the matches that draws are made of, even with said spinners. Think Hutton broke Bradman's record on such a pitch vs O'Reilly.
So why select a bowling attack for a forgone draw, while weakening your batting in the process? Can't say it's for India, Sachin and co would destroy Warne and don't see O'Reilly being much more successful.
Australia had McGill, who was arguably better than Lee, how many matches did Australia play both spinners outside of decidably spinning conditions.
India themselves don't so it that often away from the sc, the modern game is skewed towards fast bowling success. Border and Simpson is more than useful enough as second spinners in helpful conditions, and you have your full batting compliment.
It's always plugged how the Don and Gilly gives Australia a batting advantage, but having Miller at 5/ 6 somewhat neutralizes that strength. Not to mention Haydos at the top isn't that top tier level either.
Spinners less frequently make a drastic impact on games before the 3rd and 4th innings. So assume Miller os blowing that much more overs, potentially impacting his batting even more?
We're not playing on uncovered pitches and their main competition will be the West Indies and South Africa, including in those two countries.
This isn't even factoring in that while pace bowlers tend to impact the performances of great batsmen more than the reverse.
It's the exact opposite for great spinners, especially in neutral or (which is the norm) unhelpful conditions. Murali was roughed up by Lara, India and Australia. Warne by Lara and India.
So, be it unnecessarily weakening the batting, and arguably the fast bowling, to the less universally effective choice of playing two spinners in all conditions, the strategy doesn't make sense to be.
I know that not the popular opinion, but it's what I believe. He's not in the realm of an ATG batsman and all of the pacers I've mentioned are rated higher than he is, some appreciably so