The need for and value of a checklist can be very type, configuration, and operationally dependent. There is no one size fits all. If the person who owns the plane tells you to use a checklist, you should use the checklist, though it should be an approved one.
In my two planes (one of which is a 150), I do not use checklists, I use a flow check, paired with a self reminder of what I'm about to do. I think of it as "Configuration Assurance": Have I configured the plane for the next thing that I know I'm going to do with it, or should be ready for?
You won't find a Cessna flight manual checklist for a 185 reminding you to assure the wheels are retracted for landing, but there are times when doing this is vitally important. Other times, you would want to check that they are extended for landing. So the use of a checklist for the "simple" C 185 becomes operationally vital.
Another aspect of checklist use is crew co ordination. This is a complete non issue in a C 150, but the discipline can be a good beginning point. An airline will use approved checklists to create a regime which assure that crews are always working together toward the same end.
I have chosen to not fly for airlines, but I appreciate those who do, as sometimes, I need to get somewhere faster than 100MPH, and farther than 500 miles! It's nice to be able to catch a flight on something faster, being flown by someone who wants to do that for a living!