If you read the modern news and take it at all seriously, you will live in a constant fear of doing just about anything. Drinking water? You're drinking scary microplastics. Walking outside? Don't do that, the air pollution is going to give you cancer or other nasty lung diseases. Stay in and have a meal? Don't eat bread/carbs/sugar/red meat/tuna/legumes/anything processed, that will give you heart disease or cancer too, inflammation. etc etc etc.
Basically everything you can put into your body or do with your time has been associated with death or otherwise making you sick and what can the average person do about it? Basically fucking nothing.
The average person can do nothing about microplastics except be afraid of them. Also the average person cannot afford to have a healthy diet or avoid plastic and in addition, their diets are usually so bad that even if microplastics have any deleterious health effect, it's liable to be several orders of magnitude less bad than the effects of junk food or alcohol.
All the above goes to say why I think microplastics are something for scientists to worry about now because I believe the psychological impacts of all this fear are far worse than the thing itself.
Anxiety and depression, undoubtedly made worse by all the fear driven media kill more people every year or otherwise reduce quality of life far more than I believe microplastics do.