A quicker move to stability in the micro scale lends to overall stability. From that foundation of stability a better price discovery results.
I think you are saying that having HFT around leads to a stable price, say, a second sooner. So if I wait a second, there shouldn't be a difference in this regard compared to if HFT was not around, or at least the non-HFT market won't be more than one second behind. Is that what you are saying?
I could turn this on its head and say that HFT increases market maker risk since the HFT traders could move against the market maker faster than the market maker can respond to them.
Almost exactly my point. Human market making is dwindling. It is moving into the deeper areas of the book for heavy volume trades, almost a niche market. The market of providing liquidity has a finite amount of room, which is almost directly proportional to market volume. Well over 90% of HFT is MMing, which means there's been a reduction in human MMing. Many humans have been burned in the scenario you suggest, also many HFTs, thus the large reduction in HFT over the past few years. The market is rebalancing due to many HFTs losing BIG.
I may be confused about what you mean by risk. You wrote that HFT decreases MM risk since with HFT you can avoid people moving against you by being faster than them. You also write that many market makers are losing big because they are getting moved against by other people using HFT. That seems like an element of risk to me. The only way I can make these two things make sense to me is to say that SOMEONE is fastest, and then that someone can do MMing without risk since no one else is fast enough to move against them. However, that wouldn't lead to tighter spreads as I see it, since that fastest person could then exploit everyone else trying to do MM by being faster, so no one else could do MM, resulting in no competition which is going to increase spreads. Costs also increase due to the overhead of maintaining the lead in HFT. I think I'm misunderstanding your point.
Kleeneness is next to Godelness.