It depends on how you look at it. In order to have Bitcoin obtain the highest possible value and usefulness, you have to allow both its store of value and currency aspect to bloom. Stable value means merchants (same applies to payment gateways) accepting Bitcoin are less likely going to hedge their risks by selling or shorting a portion of their sales. In other words, way less selling pressure.

The more stable Bitcoin becomes, the more willing people are to actually spend it. People right now either don't spend because the value has gone down, or don't spend because they believe the price will sky rocket. It's not something that's helping Bitcoin's currency aspect. Also, the more stability there is, the less we have to deal with absolute lunatic retail "investors". I see more advantages than negative aspects.