This means that for the majority of their life, they benefit from lower stock prices. You also get a much better annual return on your investment, through dividends, when you buy under-priced stock.
Shorting deflates bubbles, before they pop. It puts the brakes on irrational markets. Working people suffer quite a bit when bubbles pop, because there are knock-on effects to employment.
Also, for most Americans, their biggest 'investment' is their home [1], with stock ownership being a distant second. That doesn't mean that we should pursue a public policy intended to drive housing costs into the stratosphere [2].
Investing into the stock market through your working life is a bet on capitalism continuing to work. Short sellers aren't going to destroy capitalism.
[1] Actually, their biggest investment is their job, but again, for some reason, policies that advocate for raising the price of labor to the moon aren't very popular.
[2] Yet, here we are, in a world where a toolshed with no running water in a coastal metro area goes for a million dollars...
Short sellers want the price of stocks to go down, which makes them bad people, because everyone currently invested in the market wants stock prices to go up.
People who haven't yet invested in the market don't want prices to go up until they do, but nobody asks for their opinion.
Also, due to the poor state of financial education, people think that a low stock price means a company will go out of business.