What if Bitcoin encourages people to stop spending more than they need to buy? Since by holding BTC you're likely to become wealthier, thereby decreasing the need to spend frivolously, people would hold onto their coins and spend them only when they had to, such as for food, shelter, and the recurring payments of entertainment--and everything else would be only if they really mean to spend, as on their business ventures or schooling or whatever else. On the other hand, with fiat, you're encouraged to get rid of it ASAP on whatever it is you need or want. Capitalism seems to favor an inflating currency, as people are more likely to get rid of their cash by either buying or investing in something else (but average Joe seems to prefer to buy.) Therefor, more money runs around, the economy (is supposed to) keep moving, la-de-da.
I think a society that's more focused on conserving their cash (and thus, their resources) is much better off than the society that must eternally spend and expand. Maybe people won't waste their hard-earned money so quickly then, and won't be so easy to coerce into giving a bank for gambling purposes--I mean, investing. This system seemed to work well when we needed to spend and expand, but now that phase is over, and the cup keeps spilling over.
Savings and capital accumulation is a benefit of a deflationary currency. But stability is important. Not going to have that this early in the game.