It's heartening to see Friday's news that the unemployment rate edged down to 7.8% last month. But let's not get too caught up in celebrations. We need to look beyond the sheer quantity of jobs being created and into the quality of those jobs – something neither presidential candidate seems very interested in talking about.

Buried in the Friday's jobs report is evidence that a disturbing trend continues: the creation of more part-time jobs, many of them low-wage, taking the place of solid middle-class careers. Positions in sectors like manufacturing continued to decline last month, replaced by new jobs in the healthcare, warehousing and retail industries. A lot of these jobs don't allow workers to rack up enough hours to earn healthcare benefits – let alone break out of poverty.

The key data in the new report can be found in a table called "A-8". It shows that more workers are in stuck in part-time jobs because their hours were cut back or they're unable to find full-time positions. The number of workers in this category shot up to 8.5 million in September – an increase of 581,000 from last month. This month's figure is nearly double what it was in September 2007, the eve of the recession.

It's distressing to think that after 20th-century labor struggles won the battle for the 40-hour work week, the 21st-century struggle is a fight for enough working hours to make a living wage. That's not what I'd call progress.

Here's another sobering number: since September 2007, the number of Americans working full-time has declined by about 5.9 million, while the number working part-time jobs has increased by 2.6 million. (The blog Zero Hedge drew up this powerful graph in June to illustrate the trend.) During the recovery, job gains have been concentrated in lower-wage occupations, which grew nearly three times as fast as mid-wage and higher-wage occupations, according to a recent study by the National Employment Law Project.

The growth of part-time and temporary work is usually a leading indicator – meaning, a sign that the job market is beginning to heal. But we've reached nearly five years after the recession officially hit, and it's time to face the fact that these employment trends are more structural than cyclical.

From academia to the retail sector, from government to warehouse work, employers are less and less committal when it comes to their workers. Offering part-time work – or even full-time jobs masquerading as freelance gigs – allows companies to offer stingier benefits packages or none at all. Those in low-wage or minimum-wage jobs often have no retirement security or health insurance. That means relying on Medicaid or even emergency room visits for illness or accidents – causing stress on workers and shifting costs from employers to taxpayers.

Benefits aren't the only problem. Workers desperate to work full time now may also be sentenced to a lower-wage fate in the future. According to a recent study by the Johns Hopkins Institute for Policy Studies, women who work in part-time jobs have fewer training opportunities and are less able to advance and increase their pay over time.

Job growth projections show that we can expect the trend to continue. The healthcare and social assistance sector is expected to add the most jobs by 2020, with retail close behind, according to the Bureau of Labor Statistics. Large segments of both industries are notorious for low-wage and precarious work. Home care workers, for example, lack minimum-wage and overtime protections, while the retail trade has faced hundreds of lawsuits for wage theft.

In the retail sector, employers increasingly want an on-call workforce that they can hire when demand is high and ignore when business is slower. Workers at companies like Walmart are reportedly "fighting for hours" at their stores, patching together irregular schedules for meager paychecks.

Of course, access to fewer hours at one job means hustling for more shifts at another. About 6.9 million Americans were working multiple jobs in September, according to Friday's jobs report. No wonder a large chunk of our workforce isn't getting enough sleep.

Continuing on this path means becoming an ever more precarious, part-time nation when it comes to our working lives. But solutions to the part-time problem aren't easy to come by. Many companies are loath to create good jobs in an uncertain economic climate, and it's cheaper and less risky to take people on part-time.

The irony is that companies seeking to cut costs are sabotaging their own bottom lines by offering unsteady employment. People working part-time involuntarily have less money to spend on goods and services, and are less able to stimulate the economy. It's a vicious cycle. Short of another economic boom that tightens the labor market, the only hope is organizing for better conditions in the workplace and the political arena.

Workers seeking more steady employment could join allies in campaigns for earned sick days or home care workers' rights to push for new protections. They could propose that part-time workers earn the same hourly pay as their full-time counterparts, and pro-rated benefits, as they do in many developed countries.

Winning these kinds of rights would be a heavy lift in a political environment obsessed with job quantity instead of quality. But to avoid a descent into low-wage, part-time nationhood, we need to dream big – like those agitators pushing to limit the workday many years ago.

• The National Employment Law Project, one of whose studies is referenced above, is a client of BerlinRosen, the communications agency for which Moira Herbst works