Same here, I see no point in switching it. In fact you could make a case that it is safer as switching to an airlock would involve pulling hoses or stoppers out and letting any nasties chilling on the lid or around the seal fall in.
I feel like someone should give a counter argument.
But so far as I can tell the only reason to switch back to an airlock is the presumption that blow off tubes are unweildy, large, and cumbersome and you''re just dying to get rid of them. But if you''re not.... Well, then...
In fact online Palmer doesn't talk about switching back. He just talks about locks vs. Tubes. He assumes the tube is forever.
I use a blowoff on anything that is going to age long term in the carboy (e.g. apfelwein). Main reason is that it takes a heck of a lot longer for a 1-gallon blowoff jug to dry out than an airlock. Fill it with sanitizer, hook it up, and forget it for a few months. All good.
If you are actually getting crud in the blow-off you should clean it out, but once it settles down you can clean it one last time and leave it.
I usually use a blow off tube for the first week or so or when I actually remember to throw an airlock on it. My blow off tubes are relatively small as I use a 3/8" tube with a cutoff ball point pen housing. Fits perfectly in the stopper hole, easily changed out and yes it seems small, but have had no blow outs in the 5+ years of brewing.
And back to more of the point, like bennie mentioned, I am gonna need it for another brew coming up! Never had any issues with stuff falling back into the brew either.
When I first started home brewing, I used a blow-off tube for the primary, and an airlock for the secondary. At the time I thought I was necessary because the primary was so "active." Nothing horrible happened and my beer was fine. Then again, maybe I was making a mistake and luckily suffered no consequences Nowadays, I only use an airlock because it's more convenient and supposedly fewer hop flavors are lost with an airlock.