First of all, most of us don't have them. The people I shoot with and converse with about S&W revolvers refuse to buy one of the later Smiths.
Yes they can be removed and I'm told there is a plug available somewhere on the internet to fill up the un-sightly hole. Then you have a hole with a plug in it on the side of your frame.
There have been claims that the ultra-light guns with the plug have locked up when maximum loads are fired through them. Those that say this are immediately doubted by those who don't mind the lock and defend S&W for having the bloody things in the first place. Since I've never owned one of them I can't say for sure, one way or the other.