Because it's the largest existential threat human civilization has ever faced.
But perhaps two things can be bad at the same time, and we should stop flooding earth with microplastics without taking away any attention from climate change. There's plenty of attention to go around. It's not like humanity is wholly committed to fighting climate change. Quite the contrary.
There are yearly events and summits with huge press coverage.
I don’t know if my company can afford to spend 3 more days per employee talking about microplastics and chemicals pollution.
I can perfectly imagine employees of a bank having to do that for the SRI rating. Then head back to their cubicle for the 280 other days and give loans for mining, road constructions, malls, etc. 99% of the time spent on business as usual isn't exactly being too much concerned about an existential threat...
That said, 3 days is better than nothing at all, and your company is likely an exception.
Regarding plastics and soil pollution there are very actionable daily and local measures we can take the reduce it. Yet nothing is done.