> I'm going to buy cars / houses / investments / goods / services when I need them and can afford them-- not based on speculation about their future prices.

Think about the prevalence of sales, and their impact on moving goods. If you need a TV, but the need is not urgent, you (okay, not you, but most people) might wait for the New Year's sales in a couple of weeks to save a few bucks. Same with cars and other appliances. Or people look for a coupon code to save some money.

If sales and coupons make sense, consumer decision making in deflationary environments should also make sense. If you don't understand why people wait for sales to purchase things, you may want to talk to some working-class people to understand what it is like to not have enough money to buy everything you need immediately when you need it.

> it was a shock

Japan has been in a gradually deflating environment for decades.