You do realize 6 of the 9 most popular games by people that play the games are "sandbox"?
There are a lot of smokers doesn't mean it is a good idea to start.
Sorry that is a bad argument from me.
I think a lot of devs make sandbox games because other devs are making sandbox games. It probably started because AAA games have had a bit of a sandbox craze. Trouble is that most devs forget that they are one person not the 100s needed for those AAA games.
I am not saying that sandbox games have no reason to exist. In a more management style game it could fit quite well Like HHS+ or to a slightly lesser extent Harem Hotel.
Trouble is that most devs have a pretty linear script in mind maybe with one or two side steps but tack on the sandbox without rhyme or reason. 'Everyone does it' is not good game design. This leads to sandbox wastelands where you are unable to do anything until you have found the content that unlocks the next content etc.
A hint system and the like can help but they are patches at best to make a bad situation somewhat acceptable. Myhtic Manor for instance sometimes has all characters needing me to do something at midday. So I need to skip morning, evening and night just to progress with say 12 out of 40+ locations being active making the rest superfluous to vist.
I honestly think that 90% or more of sandbox games on this site are worse because of it.