I can see why Kuldeep is such a tempting option because he is a left-arm wrist spinner which is a rarity in world cricket today. But given the loss of Pandya, the team balance took a hit and if he were to play India would literally have no batting after the 6th wicket, an area where several teams have competent allrounders/bowlers who add valuable runs. Some members are saying Kuldeep should play the next test, but the same thing might happen as it did at Lord's where batsmen didn't even have to pick his variations to bat on a green track. I'd only consider playing Kuldeep at Sydney where the ball actually turns a fair amount and it's the most spin-friendly surface in Australia. For now, it seems completely unnecessary with the job Ashwin has done at Adelaide.
Ashwin receiving flak is quite bizarre. He batted for 76 balls for 25 runs but he allowed Pujara to take control and score crucial runs. And on top of that, as others have said he held up one end and picked up key wickets. Calling Nathan Lyon a wicket-taker and comparing him to Ashwin in this aspect doesn't make sense. Lyon picked 4 wickets that were thrown away in the second innings of the Indian innings, but Lyon didn't have the support from his fast bowlers. Ash built pressure which allowed the seamers to capitalize and take their chances.
One thing I've noticed that the last 5-6 years in Australia is the seamers are the main wicket-takers, but the spinners get little assistance and keeping the pressure is what they are supposed to in unhelpful conditions like Australia. It's how Nathan Lyon operated in the last few years with him sustaining the pressure on the batsmen and the fast bowlers taking the wickets. There's nothing else that is required from a spinner in Australia. Playing Kuldeep for Perth is overkill and there is no logical reason to play him with Ash in the side.