The question could have been on Graphic Design Exchange.But, since you are already here take an answer home.
There are many revolutions that have happened in Design & Digital Industry on how we can make the look and experience better to make a user feel more comfortable with the device they use that invloves a screen.So, in this regard, there was one study that extensively took place and today it a new normal for having Shadows in the UI.
The research was conducted by Google Design team that added much more significant reasoning on having something like shadow. This has a long history and conceptualization involved on why we have shadows. Do take a look at some videos using the links below:
- https://www.youtube.com/watch?v=rrT6v5sOwJg - 6 min video Material Design.
- https://www.youtube.com/watch?v=w2JUhDd0CAA - 3 min video How shadows were added.
These two videos can make you feel more satisfied with the reasoning and you conclude can conclude if it good or bad.
In my opinion : Depending on the purpose, it is a design decision to make.