I usually just upload images of my business to GMB without the title but have always wondered if its worth the effort to title them.
Not really, it is not a ranking factor. 
Maybe not a ranking factor but it adds context. People looking at your profile will now know what they are looking at. This may sway them to convert.
Roberto replied
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 Roberto  Adding titles to images is not a direct ranking factor in that merely adding titles does not directly result in a rankings increase. You points are very valid, and a great reason to include them because not everything is about better rankings, etc. Sometimes it's good practice simply because it helps customers 😃 
ClutchJunk replied
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