So I've got this list of items I'm displaying in a tableview and we've got a single thin line between items that divide them. I've got a request to remove all of the lines and have them all bleed together. I feel like this is not an intuitive move, what are your thoughts on using a line to divide items in a table? If you were to explain this to a client what would your feedback be?
It really depends on the data being presented (primarily, how many records are shown, but also, for instance, how big the space between raws are).
Lines in tables are, essentially, an implementation of Gestalt law of enclosure (in which a common background would also serve the same purpose; ie, raw stripping). They help distinguish one raw (or column) from another.
Lines (especially bold ones) add unwanted visual noise. But without them, it may be hard to distinguish between adjacent raws or columns.
But it is possible that the distinction will be clear enough even without lines or different backgrounds (just like you distinguish between different lines of text in this post).