I will respond with one reason to consider for removable magazines.
Consider the home invasion scenario where you have multiple homes invaders with the intent to harm you and yours. The majority of malfunctions within a semi-automatic firearms tend to be the feeding device. A removable magazine is essential to you remedial actions when dealing with a malfunction in a gun fight. If Tap/Rack/Pull doesn't work, the next option is, drop the mag, clear the jam, insert new mag, go.
Again, this is one reason to consider. I am sure there are many more reasons individuals can come up with. For me in my home, I always have multiple magazines loaded and ready to go for every self-defense firearm in my home.