If someone doesn't take good care of their yard and/or there is an infestation of sorts (E.g. ticks in relation to lyme disease, beetles destroying native plants,etc) some governments may even require you to spray the yard.
Those can be handled in other ways. For instance, seal openings to the outdoors, keep the house clean so ants aren't getting food, lay out ant poison that they take back to their nests so it's more targeted, spray diluted citrus oils in the places spiders like to hang out since they don't like the smell, etc.
Some people have anaphylaxis to bee stings. There are other ways to deal with that, sure, but I have a hard time blaming someone for trying to get rid of an immediately deadly hazard.
If we're talking about the USA, mosquitos are not dangerous enough to warrant taking any action whatsoever. Of the dozens and dozens of species of mosquito, there are less than a handful that are potentially dangerous, and only in a small region, and only sometimes.
There is no reason to spray chemical toxins in a yard because of mosquitos.
If you want to take action to reduce mosquito numbers, start with pooling water. They are often able to breed in ruts left by vehicles driving on paths where they aren't supposed to be.
Zika [1], West Nile, Encephalitis, Dengue, Chikungunya have all shown up in at least Texas and Florida in the past few years [2]. While I agree reducing pooled water is the most important vector control action you can take, it seems likely that the US will not remain immune from arboviruses in the long term. Thankfully the vast majority of cases continue to be travel-related but there are small numbers of locally-acquired disease being reported since ~2013.
Which is to say in those areas at least you should most definitely wear long clothes, wear an approved repellent, and avoid sleeping in unprotected areas (rooms with open windows without screens, outdoors without netting, etc).
Mosquitoes are pretty generally determined to be bad. Their value to any ecosystem is difficult to justify. However, many methods used to eliminate them have collateral damage.
