It is if you want the ability to scan down the page and decide what links you're interested in by using the thumbnail.
If you are interested in text posts, it makes sense to scan the titles. If you are interested in images, it makes sense to scan the thumbnails.
Having them blurred adds extra work and is an extra annoyance - and since there is an individual user-level setting for whether or not you want to see NSFW content, it makes no sense to mandate the blurring.
raoulvolfoni
InLikeClint
NotTheOnlyGamer