Because your paycheck is someone else's "spending money."

Edit: Meaning that, presumably, you like being paid. So you probably don't want to incentivize being paid less, or not at all. Deflation does both of those things.

It may not be bad, economics involves a lot of unfounded speculation IMO. It's true that deflation would encourage delaying certain types of spending but that is already the case with electronics and some other types of goods. But that has not led to the downfall of society.

A deflationary economy would be a drastic change from the system we operate under now but I don't think it would be all bad. Maybe in a deflationary economy people would feel like they could actually save money. Or it could put an end to the 40 hour work week. I doubt demand of necessities would change much in a deflationary environment: food, medicine, shelter, etc.

I think I agree. A lot of it is models that don't predict things ( but that is waved away by saying those are not complex enough to reflect real life ), psychology and opinions.

Personally, long term I am perfectly willing to accept that deflation is a bad thing for society, but at this time? We should welcome deflation with open arms. Things are way out of whack already and decent price correction is needed for just about everything.

Causes a positive death loop that leads to huge demand shocks.

You only have to look at Japan for the last few decades to see what the long term effects of deflation look like. Negative economic growth, few job opportunities for young people, investment and lending are de-incentivized so innovation and industry growth moves to other countries, while owning property becomes a liability, etc. Managed decline is about the best case scenario for a deflationary economy.