CRT monitors and TVs are getting very dated and take up a lot of room. Some people still keep a large CRT TV for retro gaming, but not everyone has the room for this or wants to keep one around.
You can get a decent image onto a modern LCD display but it can take some effort and can be more difficult for some retro systems. Over the last few years I've tried a few different hardware solutions for achieving this and will explore each and my findings in this thread.