Coins are not or shouldn't be profitable. The use of those coins should be, e.g. fees, loans etc. Crypto can transfer value cheaper than fiat, so I believe that is where the real value and promise is. Reducing friction and with that improving markets.
Parking temporarily protects the coin from large sell-offs when the NSR value is already depressed. It is a last resort to ease the pain, not taking away the problem, just spreading it out the cost in the hope that better times are ahead.
I agree that focus shouldn't be on holding but on usage of the stable coin. Unfortunately hedging on exchanges being the main target is not the most profitable one. It is relatively simple to do but it comes with great risk, due to volatility. The only reason would be to maintain liquidity to maintain the peg.
Maintaining reserves is always required to some extent and is more a emotional than a rational issue. People want assurances that when they sell they get their money back. If everyone sells at the same time due to panic there won't be enough to pay back.
I believe more thoughts need to go into modelling the reserves. Reserves are only expensive when not used, there is challenge to make them cheaper or even profitable. E.g. by short-term lending. We had all these discussions in this forum before, but it never happened for some reason. The volatility and the (regulatory) risks are apparently still too high to make this profitable for anyone.