People doing "useless" jobs might acquire the skills to do other and more useful jobs in the future. Keeping people unemployed has a high cost in the form of loss of skills over time, mental health etc.
If you don't keep things going you might risk losing some people forever as their skills become so obsolete and their motivation and work capacity destroyed.
Companies will usually not higher long term unemployed so that is why many people can get permanently lost to the labour market.
This is likely why I'll likely never be able convince myself to take a break from programming until retirement.
Unless, of course, today's chatbots evolve to write code better than we do. Or at least cheaper.
Implementing such a program in that way though requires a fair amount of attention. If it ends up not reducing unemployment, that means it is diverting workers from other industries, which doesn't necessarily mean it is a bad program, but it's a different kind of thing.
More jobs, more wages, more actual money in the economy to displace credit cards and pay down household debt, and improved infrastructure may well see new business opportunities come into existence.
I could only imagine the abuse with a gov't directed jobs program!
Corruption is a human problem, not a government or corporate problem.